Adding comets to level import & export
Updates to stranded astronaut following behavior
Overhauling player control
omg. camera.
Updates to player controller; per planet gravity; discrete jump strength; limited jetpacks
Added pausing; minor tweaks to GUI; working on map view
Added document listing controls
Sprite implementation and scaling planets
Merge branch 'Sprites' into test
Planet & Astronaut sprites merged
Some fixes; added reset; tweaking camera; comet-adding fixed