Revert "New Graphics stack ftw"

This reverts commit e2cd7e9a3b95e13dc7089fcdedecf428cac93eda.

Conflicts:
	core/src/io/github/vovinhd/hexacrush/simulation/CoordinateGrid.java
	core/src/io/github/vovinhd/hexacrush/simulation/Simulation.java