[Bf-python] Contrib Addon Review: object_edit_linked

[Campbell Barton]

Having a quick way to load a linked file is very clearly a missing
area in blenders library system - and very useful to have,
in fact for durian I wrote a similar script - though it worked a bit different.

Scripts like this are tricky because you end up trying to hide from
the user that you are save-load, reloading... its very clunky and
blender has no pretty ways to edit library data and write it into a
file.

The script I wrote just loaded another instance of blender and moved
the 3d viewport to display the linked object - but didnt attempt to
manage save/reload stuff.

So tentative approval for this script, but Id like to do code-review
first, there are some minor issues I spotted.
- path comparison, better use `os.path.samefile`
- assumes the object is in the active scene of the other blend file -
not always the case.
- `Edit Linked` operator should be clear that it saves your blend and
loads a new one. (users may not want to save at the current state).

--
- Campbell