Blender Git Loki

Fix T52685: Flip names for bones its not working.

Flip names operator changed in rB702bc5ba26d5, to some sensible
behavior. But this breaks common workflow of 'duplicate part of the
bones, scale-mirror new ones, and flip their names'.

So now, instead of doing this in two steps, trying to guesstimate which
bones should get which name, just add option to flip names to duplicate
operator itself. Simpler, safer, and much, much more consitent behavior
and predictable results.