Recycle garbage groups
Minor (log and messages)
Nice refactoring: goban is Group factory now
Removed minor unused variables
More clever speed test (not using game controller)
Calibrate's expected time moved to test file

Allows to create new tests without having to do the maths when different
machines are used.
No more controller in speed test + new game 63 moves
goban script includes now stone and group
Controller shows history and dbg even after EOG