2.5 - More armature/bone operator tweaks

2.5 - More armature/bone operator tweaks

* Restored quick operators for moving bones between layers and switching visible armature layers. The popup used here (based on the layers template) is not optimal yet - you can click on multiple layer buttons to enable/disable them, but you need to move your mouse outside the area for it to confirm.

* Separate armatures works again. I've tweaked the arguments to ED_object_duplicate() to make this work (besides, the other users of this wouldn't have been affected).

* Added some missing special (transform) operators to the menus + keymaps