Fix scanline rendering bugs.

Add:
	src/graphics/graphics.c
		-Fix bugs in `scanlineRender()`, which caused either quasi-infinite
		loops (which presumably terminated only after double overflow) or
		resulted in the lowest vertex of a triangle being identified as the
		highest.

	src/graphics/matrix.c
		-Add additional triangle for every triangle currently added, because the
		sphere was only half-filled.