[sensor] Fix ptu_posture incorrect handling of scene with multiples ptu

Instead of matching the exact name, try to match a regexp which consider
possible automatic renaming from Blender.

Fix #536

Based on a suggestion of Andrzej Pronobis in #537
[testing] Add a non-regression test for multiples ptu in a scene (#536)
[builder] Make armature morseable by default

Fix #517