Now draws the "lives" text
Also did a lot of back end stuff in preparation to draw the life tanks
The lives tanks now appear on the top right of the screen
....But they don't update quite yet. Hoorah!
Lives display now works
Also changed the top boundaries.
Merge branch 'lives'

Conflicts:
	space_invaders/src/display.c
	space_invaders/src/space_invaders.h