Released GIL during TSR Planner.

This prevents unnecessary hangs during planning when using python
threads.  I see no cases where this would not be necessary.

Author: psigen

src/prpy/planning/tsr.py

@@ -101,7 +101,9 @@ def PlanToTSR(self, robot, tsrchains, tsr_timeout=2.0,
             ik_param = IkParameterization(
                 tsrchain.sample(), IkParameterizationType.Transform6D)
             ik_solution = manipulator.FindIKSolutions(
-                ik_param, IkFilterOptions.CheckEnvCollisions)
+                ik_param, IkFilterOptions.CheckEnvCollisions,
+                ikreturn=False, releasegil=True
+            )
             if ik_solution.shape[0] > 0:
                 ik_solutions.append(ik_solution)