- add TinyMutex to resolve the issue that we can not operate the virtools group infos of 2 individual objects.
* use this new class for all class need resource mutex, such as ballance element, bme materials and etc.
- add CollectionVisitor to resolve that blender have bad document and type hint for runtime bpy.types.CollectionProperty.
* now all visit to CollectionProperty are delegated by this class.
- add extra transform for rail creation.
- remove scale from extra transform because it is rarely used. because Ballance can not handle the physicalization of scaled object.
- add extra transform properties (translation, rotation and scale) for bme creation operator. this is good for "what you seen is what you gotten" and can increase user experience when add bme protorypes. please note these extra transform is applied to object after moving to cursor, not the mesh self.
- fix a weired bug that bme creation execute() may get outdated configurations when switch bme type in pop up window. the solution is simply adding an extra outdated flag checker at the head of execute(). but i have no spare time to research whether this patch is correct for this bug.
bring ballance virtools helper used fix_texture (renamed as fix material to correspond with the real object operated by this function) into blender plugin.
