Add linear drag force to simulate fluid velocity
Small refactoring. Work to do yet...
Remove unused sample methods
Update menu fonts

Font changed from Consolas to Righteous.
Add a new splash image and change animations
Small Box2DFactory refactoring to allow users set the center of a shape
Remove unused imports
New sample to show how to make a player jump and double jump

We still have to prettify this sample...
Update code version to v0.6.0
Remove unused import
Change jumping sample name
Remove menu animation

This animation was causing problems in mobile devices. Will be removed
until we find the cause.