Blender Git Loki

Partly revert own rBb97c567c1df1e, clear_proxy is actually safe.

This is very confusing, in fact, and rna tooltip was wrong,
BKE_object_make_local_ex actually ensures we never have several proxies
of same object, since it always clears proxy when it has to copy object
to make it local...

What that RNA function is probably missing, though, is same logic as in
BKE_library_make_local to actually remap proxy from old linked object to
new local one.