Fix tolower and toupper.
Fix isxdigit.
Add strcasecmp and strncasecmp.
On strncmp and strncasecmp, handle the max. size being zero and correctly return 0.
Add strcasestr.
Fix strstr and strcasestr.
Convert to Unix line endings, in an attempt to fix the merge conflict.
Merge remote-tracking branch 'upstream/master' into libcFixes

Conflicts:
	libc/ctype.c
	libc/string.c
Merge pull request #14 from gbl08ma/libcFixes

libc string function bugfixes.
Merge branch 'master' of https://github.com/Jonimoose/libfxcg into exitFix