Improved FallingBlock

**The issue**
Currently you cannot modify the behaviour of the ````FallingBlock```` after the creation. You have to track the falling block and apply your requested behaviour in an event. The predefined behaviour is required in order to create simple environmental behaviour like a vulkano or fountain.

**PR Breakdown:**
This PR adds 4 methods to Falling Block:
* canPlaceAsBlock() : boolean
* setCanPlaceAsBlock(boolean)
* canDropAsItem() : boolean
* setCanDropAsItem(boolean)