sha1_io: inline functions
hash: Replace struct with a primitive type for hash values.

Remove the struct hash_entry and define a new type for hash values.
Most likely we will only need one member in this struct. and instead
of just using unsinged int. let's name a new type for clarity.
Adding xalloc
Makefile: add -D__DEBUG__ symbol.

xalloc.c uses this symbol to provide additional debugging
information. This patch adds support to make to define this symbol
when running:

$ make DEBUG=1
Adding dynamic array datastructure.
hash.c: use xalloc
Adding utils.c.
dlhist.c: use file_cmp from utils.h instead of static path_cmp.
Adding version.c
Adding additional command line flags for help and version.
Adding version generation script for Makefile.
Adding hex.c
compiler/integer.c: Adding a integer parser.