Added more new graphics

-Added a graphic for Earth
-Made the grid background transparent
-Added new bullet graphics for the aliens
-Added a new UFO graphic and animated it
-Fixed that cut off pixel issue with the spritesheet
Merge branch 'master' of https://github.com/CorundumGames/Invasodado

Conflicts:
	game/ingame.py
Merge branch 'master' of https://github.com/CorundumGames/Invasodado
Resolved merge conflict with enemy.py
Implemented particle system

-Blocks now release particles upon explosion
-Implemented starfield to use particles
-Also redid backgrounds (but still messy)
-Grid is now transparent