* Added a context menu on the buttons including Clear & Restore Default
* Allow clearing (unsetting) inputs. Added a Clear All button
* Allow restoring a single input to default (instead of all)
This avoids a redundant std::string construction if a key doesn't exist
in the map already.
e.g.
data[key] requires constructing a new default instance of the value in
the map (but this is wasteful, since we're already setting something
into the map over top of it).
ameerj
zhupengfei
Lioncash
James Rowe
wwylele