Added G and dt to gravity simulation, masses and initial velocities to planets, created a stable system, gave the planets different colours
Merge
Modified simGrav to derive dt value from tpf, so that the speed of the simulation is the same regardless of the frame rate
Added line (commented by default) to fix frame rate to test the game speed under different conditions
Merge pull request #18 from lechszym/master

Make the simulation speed independent of the framerate