gitignore: Add a gitignore file

Currently we ignore *.o and *.a.
Makefile: Add -fstack-protector

Compile with stack protection.
Makefile: Search 'include' dir for headers

Add a -I option to the CFLAGS to search 'include' for headers.
gopt: Add gopt to the library

Gopt is public domain code to parse command line arguments.