Added Xcode target to build cat2html utility.

Removed pregenerated cat2html.c, prebuilt cat2html executable and old
Project Builder makefiles.  Defined new "cat2html" target and added
custom Build Rule for Lex source files to build "cat2html.l".  Made
the ManDrake target depend on the cat2html target and added the
cat2html product to the ManDrake bundle resources.

In cat2html.l, defined YY_SKIP_YYWRAP, included unistd.h and removed
old declarations for getopt(), optarg and optind.