Update unit-tests, add color to terminal output.

Add:
	src/unit_tests.c, test/*.csv
		-Update `testAddPolygons()`, `testAddSphere()`, and `testAddTorus()`
		unit tests to test against the results of the updated corresponding
		functions (which render each figure differently after the implementation
		of backface-culling, due to fixes to some bugs that became apparent).
		-Unit-tests do not yet account for which points are visible (ie,
		backface culling has no actual impact on them), testing only against the
		points present in a given matrix (before they're plotted on the screen).

	src/unit_tests.c
		-Add statements to print success/failure messages in color, if a given
		terminal supports them.

	src/engine.c
		-Remove now obsolete `test()`.