fixed cubes cutter & boolean on keypress

fixed top and bottom layers of cubes cutter, now it is expanding to
"infinity" on y and -y.
boolean operation and draw of result is now done on key press
cleaned up setup a little

moved boolean operation and drawing of pieces to update(), on key press
it performs operation
problem on: puzzle.cpp

It is getting empty info when I pass on the slicer->pieces[i]!!!
on the main it has the data...but when it is passed onto puzzle object,
it doesn't have data on pieces[i]!!!
solved group** data loss

slicer->getPieces() retunrs a copy of the ** pieces[], to pass along to
whoever needs one.
every time this happens:
sgCGroup *result2 = (sgCGroup*) aux[i]; (to break a group)
aux[i] gets lost!!! does this always happen? how do I prevent data loss?
stable version

it's doing boolean on key press.
drawing objects using a copy of mySlicer->getPieces();
on the works::: putting the copy of the pieces into cubies.
Merge remote-tracking branch 'origin/slicing'