Fix surface detection, last line of map bug.

Ref:
	src/graphics.c
		-refactor while-loop in scanMap() into for-loop.
Fix:
	res/lvl1.map
		-additional line was printed at the bottom because Vim silently
		appends a newline to the end of any file.

	src/termcrate.c
		-onSurface had an off-by-one error. Fixed, and now
		surface-detection works properly.

	src/graphics.h
		-increase MAP_WIDTH by 2; the original width of 176 only
		accounted for all chars, but not the hidden newline (and,
		presumably, an end-of-line null byte). Overflow ensued, silently
		inserting new rows, and consequently, the last line of the map
		was never read into mapBuf and surface detection was off by
		one or more, depending on how many 176-width lines preceded your
		position. Changing macro to (176 + 2) fixed everything.