Challenge 1: "Write a program which prints out all anagrams for a given word."

Note: I assume that we'll need a wordlist to judge whether a rearrangement
of letters is actually a word, /usr/share/dict/words is the obvious one
to use.  The simplest way of solving this problem is to use alphabetically
sorted SIGNATURES of words - simply the bag of letters in the word sorted.

So "hello"'s signature is "ehllo".  The important thing for anagram purposes
is that "ehllo" is the signature not only of "hello", but of any other anagram
of hello too.

So: calculate the signature of the given word, then for every word in the
dictionary (of the right length if we want to save time), calculate that
dictionary word's signature - then print out the dictionary word if it's
signature is the sameas the given word's signature.

Note that ch-1.pl takes two command line arguments: the first is the
word, the second is the optional filename of the wordlist to use,
if it's not given then /usr/share/dict/words is used by default.


Challenge 2: "Write a program to find the sequence of characters that has
the most anagrams."

That's rather badly worded, but I choose to interprete it as "find which
word in a wordlist has most anagrams also in that wordlist".

Note that ch-2.pl takes a single optional command line argument: 
the filename of the wordlist to use, if it's not given then
/usr/share/dict/words is used by default.

So: Calculate the signature of every word in the dictionary, building %anag:
a mapping from signature -> list of words with that signature, and keep track
of the longest word list of any signature (i.e. the biggest anagram set so far)
as we go.  Print out the signature with the longest word list at the end.