Add Basic Jump function

Jumps still need to be deleted when they're over.
Add getSpritesCopy() to Field
Work on Jump Function

We encountered a problem with killing the SpActions
Redo all action inheritance (part 1)
Add auto-deletion for sprite actions
Limit current Jump to one
Redo all action inheritance (part 2)
Merge pull request #7 from Bernardstanislas/fluidity

Add getSpritesCopy() to Field
Merge pull request #8 from Bernardstanislas/jump

All action system redone properly, new jump action with proper keyboard input, auto-deletion of finished actions