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.
Revert "fix memmove my implementation"

This reverts commit 9e1ccc345fcdea782be986efb46236de9f791472, which appears
to be broken (see issue #24).

Conflicts:
	libc/string.c