Added falling platform class.
Updated check Magnet function to not allow lander to attract to other magnets within same structure.
Added bottom boundaries to level 4 data.
Updated interaction callback for falling platform.
Updated collidedwithBoundary function to break lander joint
Added falling platforms back to space after player has lost life.
Updated gravMass to be changed only when lander takes off and when it collides with another structure.
Finished falling launch platform.
Merge branch 'feature/Falling_launch_platform' into develop