Changed callbacks to return space, arbiter instead of arbiter, space to be compatible with pymunk
Merge pull request #4 from nskrypnik/master

Poly class and misc changes for Pymunk API capability
Merge pull request #6 from tito/pymunk_callback_compatibility

Pymunk callback compatibility
Merge pull request #5 from nskrypnik/master

Added constraint and pivot joint, thanks Niko!
Fixed constraint creation code
Added constraint callbacks setable by setting pre_solve and post_solve properties, it is a little ugly
when removing a constraint from a space it now removes itself from the global used to pass callbacks from C to Python
Merge pull request #7 from tito/fix_constraint_removal

Fix constraint removal
Removed excess print statements
Merge pull request #8 from tito/fix_constraint_removal

Fix constraint removal
Cleaned things up a little based on tito's advice
Merge pull request #9 from tito/fix_constraint_removal

Fix constraint removal
Fixed callback code so that more than one space is supported
Merge pull request #10 from tito/fix_callbacks_and_multiple_spaces

Fix callbacks and multiple spaces
Added slidejoint and exposed pivot and slide joint properties
Merge pull request #11 from tito/more_constraints

More constraints
Added GrooveJoint, PinJoint, DampedSpring, added set methods to Constraint properties
Merge pull request #12 from tito/more_constraints

More constraints
Implementation of shape_query and bb_query functions