Update documentation

1. File name comparison method:
 - initially ignore white space and punctuation characters
 - run test for numeric values
 - if the remaining substrings match in case-insensitive compare, compare case
 - if they still match, see which one has more prefix symbols
 - if they still match, run a case-sensitive compare on complete strings

2. Fixed xstrcmp() to return diff instead of 0 and -1.

Results in even less memory usage. The names are appended one after another.
The offsets are reset when the location of the memory changes die to realloc().

Other changes:

1. Use a debug mode print to measure time.
2. Remove redundant prefix when printing pointers in debug mode.