Re-license project as LGPL (#157)

* add licence files & a few misc chores

* add license notices & run auto formatter

1 files changed, 157 insertions, 0 deletions

diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 00000000..6e75f84c
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,157 @@
+### GNU LESSER GENERAL PUBLIC LICENSE
+
+Version 3, 29 June 2007
+
+Copyright (C) 2007 Free Software Foundation, Inc.
+<https://fsf.org/>
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+This version of the GNU Lesser General Public License incorporates the
+terms and conditions of version 3 of the GNU General Public License,
+supplemented by the additional permissions listed below.
+
+#### 0. Additional Definitions.
+
+As used herein, "this License" refers to version 3 of the GNU Lesser
+General Public License, and the "GNU GPL" refers to version 3 of the
+GNU General Public License.
+
+"The Library" refers to a covered work governed by this License, other
+than an Application or a Combined Work as defined below.
+
+An "Application" is any work that makes use of an interface provided
+by the Library, but which is not otherwise based on the Library.
+Defining a subclass of a class defined by the Library is deemed a mode
+of using an interface provided by the Library.
+
+A "Combined Work" is a work produced by combining or linking an
+Application with the Library. The particular version of the Library
+with which the Combined Work was made is also called the "Linked
+Version".
+
+The "Minimal Corresponding Source" for a Combined Work means the
+Corresponding Source for the Combined Work, excluding any source code
+for portions of the Combined Work that, considered in isolation, are
+based on the Application, and not on the Linked Version.
+
+The "Corresponding Application Code" for a Combined Work means the
+object code and/or source code for the Application, including any data
+and utility programs needed for reproducing the Combined Work from the
+Application, but excluding the System Libraries of the Combined Work.
+
+#### 1. Exception to Section 3 of the GNU GPL.
+
+You may convey a covered work under sections 3 and 4 of this License
+without being bound by section 3 of the GNU GPL.
+
+#### 2. Conveying Modified Versions.
+
+If you modify a copy of the Library, and, in your modifications, a
+facility refers to a function or data to be supplied by an Application
+that uses the facility (other than as an argument passed when the
+facility is invoked), then you may convey a copy of the modified
+version:
+
+-   a) under this License, provided that you make a good faith effort
+    to ensure that, in the event an Application does not supply the
+    function or data, the facility still operates, and performs
+    whatever part of its purpose remains meaningful, or
+-   b) under the GNU GPL, with none of the additional permissions of
+    this License applicable to that copy.
+
+#### 3. Object Code Incorporating Material from Library Header Files.
+
+The object code form of an Application may incorporate material from a
+header file that is part of the Library. You may convey such object
+code under terms of your choice, provided that, if the incorporated
+material is not limited to numerical parameters, data structure
+layouts and accessors, or small macros, inline functions and templates
+(ten or fewer lines in length), you do both of the following:
+
+-   a) Give prominent notice with each copy of the object code that
+    the Library is used in it and that the Library and its use are
+    covered by this License.
+-   b) Accompany the object code with a copy of the GNU GPL and this
+    license document.
+
+#### 4. Combined Works.
+
+You may convey a Combined Work under terms of your choice that, taken
+together, effectively do not restrict modification of the portions of
+the Library contained in the Combined Work and reverse engineering for
+debugging such modifications, if you also do each of the following:
+
+-   a) Give prominent notice with each copy of the Combined Work that
+    the Library is used in it and that the Library and its use are
+    covered by this License.
+-   b) Accompany the Combined Work with a copy of the GNU GPL and this
+    license document.
+-   c) For a Combined Work that displays copyright notices during
+    execution, include the copyright notice for the Library among
+    these notices, as well as a reference directing the user to the
+    copies of the GNU GPL and this license document.
+-   d) Do one of the following:
+  -   0) Convey the Minimal Corresponding Source under the terms of
+         this License, and the Corresponding Application Code in a form
+         suitable for, and under terms that permit, the user to
+         recombine or relink the Application with a modified version of
+         the Linked Version to produce a modified Combined Work, in the
+         manner specified by section 6 of the GNU GPL for conveying
+         Corresponding Source.
+  -   1) Use a suitable shared library mechanism for linking with
+         the Library. A suitable mechanism is one that (a) uses at run
+         time a copy of the Library already present on the user's
+         computer system, and (b) will operate properly with a modified
+         version of the Library that is interface-compatible with the
+         Linked Version.
+-   e) Provide Installation Information, but only if you would
+    otherwise be required to provide such information under section 6
+    of the GNU GPL, and only to the extent that such information is
+    necessary to install and execute a modified version of the
+    Combined Work produced by recombining or relinking the Application
+    with a modified version of the Linked Version. (If you use option
+    4d0, the Installation Information must accompany the Minimal
+    Corresponding Source and Corresponding Application Code. If you
+    use option 4d1, you must provide the Installation Information in
+    the manner specified by section 6 of the GNU GPL for conveying
+    Corresponding Source.)
+
+#### 5. Combined Libraries.
+
+You may place library facilities that are a work based on the Library
+side by side in a single library together with other library
+facilities that are not Applications and are not covered by this
+License, and convey such a combined library under terms of your
+choice, if you do both of the following:
+
+-   a) Accompany the combined library with a copy of the same work
+    based on the Library, uncombined with any other library
+    facilities, conveyed under the terms of this License.
+-   b) Give prominent notice with the combined library that part of it
+    is a work based on the Library, and explaining where to find the
+    accompanying uncombined form of the same work.
+
+#### 6. Revised Versions of the GNU Lesser General Public License.
+
+The Free Software Foundation may publish revised and/or new versions
+of the GNU Lesser General Public License from time to time. Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Library
+as you received it specifies that a certain numbered version of the
+GNU Lesser General Public License "or any later version" applies to
+it, you have the option of following the terms and conditions either
+of that published version or of any later version published by the
+Free Software Foundation. If the Library as you received it does not
+specify a version number of the GNU Lesser General Public License, you
+may choose any version of the GNU Lesser General Public License ever
+published by the Free Software Foundation.
+
+If the Library as you received it specifies that a proxy can decide
+whether future versions of the GNU Lesser General Public License shall
+apply, that proxy's public statement of acceptance of any version is
+permanent authorization for you to choose that version for the
+Library.