Add rotation, screen conditional. Fix translation.

Add:
	src/matrix.c
		-add createRotation(), which creates and returns a matrix for rotation
		about a given axis and argument

	src/matrix.h
		-add macros for each axis, currently only used in calls to
		createRotation().

	src/screen.c
		-add conditional to drawPixel() that exits the function if either the x
		or y argument is outside of the screen boundaries.

Fix:
	src/matrix.c
		-createTranslation(), in updating the last column of the 4x4 translation
		matrix with dx, dy, and dz values, was only updating the first row
		because the row values weren't changed per line after the original line
		was copy-and-pasted three times.