Pulls common functions into a Utils module

Moves show and read functions for hex and base64 into
Matasano.Utils. Modifies and prunes import lists.
Sets -Wall build option
Updates definitions

Adds error handling and introduces some minor efficiency gains.

Note: The semantics of readHex are now changed, the function will no
longer operate on strings of odd length, these are assumed to be invalid
in a cryptographic context, i.e., you wouldn't encrypt half a byte.