added a hexahedron to show hexBlocks
show edges on patches
added function in hexblocker to remove a block.

o No GUI button yet.
o HexPatches no has regular pointers to hex block since they are not
  created in HexPatch.
Added a new InteractorStyle which allows selection of HexBlock, HexPatch or HexEdge

Further the user can rotate the model while selecting. There are three modes:
o single - only one object can be selected
o pair - only two can be selected, the second is colored blue
o multi - any number can be selected.

Deselection is done with the right mouse button.
added gui button to delete blocks
added icon for the delete blocks action
added function for controlling visibility of patches
added visibility actions for HexEdge, HexPatch and HexBlocker
reworked the method of deleting objects
Removed obsolete interactorstyles

All block, patch and edge selection is now handled in
InteractorStyleActorPick.