Blender Git Loki

* New tool - Join as Shapes

Available in object mode (Object -> Join as Shapes), only works for meshes at
the present. Will merge all selected objects as shape keys on the active object,
if the vertex count is the same.

This does not keep references to the external objects like in some applications,
rather it's a quick way to update the shapes on the active object (perhaps after
importing new versions from external applications).