[#538] cleaned the level definition of the old tile based collision information
[#565] added automatic collision response handling

Using the `isSolid` and `isHeavy` flags to define the behavior, as
discussed in the corresponding ticket
[#538] platform (or other specific) style collision can now be defined by the end user
[#565] changelog update
[#573] renamed `me.Sprite.resize` to `me.Sprite.scale`