- Added RigidConstraint.
- Depricated some methods (get_result, get_constrainedness) and
added some new methods (get_solution, get_cluster, get_status).
Removed old SelectionConstraint and renamed FunctionConstraint to SelectionConstraint
Depricated ClusterSolver2D
Small bugfixes in cluster ClusterSolver3D
Renamed solvergui directory to workbench
Renamed solvertest directory to test