0.1: Tons of refactoring/cleanup

Made the whole thing a little cleaner and put in the first steps to the
goal API.
Bugfixes

More refactoring and bug fixes.
Change FPS measurement.

Before, FPS was measured with the delta time given to love.update(),
which is only accurate to the millisecond, and was outputted with
print().

Now, FPS are measured with love.timer.getMicroTime(), which is accurate
to the microsecond, and is drawn as text directly to the screen.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	camera.lua