Create graphics file; update makefile with flags.

Add:
	src/graphics.c
		-will contain all graphics-related functions (currently,
		render(), scanMap(), and clearScreen()).

	makefile
		-add optimization flags, and project root dir to header include
		path.

Mod:
	src/graphics.c
		-add screenClear() and cursor reset to render()
Ref:
	src/termcrate.c, src/graphics.c
		-migrated graphics-related functions from termcrate.c to
		graphics.c, for greater flexibility.
		-substitute relative paths (e.g. "../src/termcrate.h") with
		"src/termcrate.h", by adding the root dir (termcrate/) to the
		compiler's header include path. See makefile