Step 1 of the g_UserUnit global eradication. This commit includes
basic hookup of hotkeys, units tool-buttons and grid dialogs.
(cherry picked from commit e0500ab)
* Refresh the view only when changes are made in the caller frame.
* Allows recreate a new instances when try to open the 3D view from a frame taht is not the initial caller
* Remove duplicate code in kicad frames.
Frame, dialog and config file couldn't agree on whether to use
internal units or not.
Frame now stores internal units, and they're now mapped on the
way in/out of the config file. Dialog was already assuming they
were stored in internal units (though they were previuosly not).
Fixes: lp:1751435
* https://bugs.launchpad.net/kicad/+bug/1751435
Fixes a bunch of errors:
- libedit and libbrowser would zoom to bounding box but centre on canvas
- libedit, libbrowser and gerbview didn’t take the scroll bars into account
- pcbnew didn’t take scroll bars into account or apply the 10% margin
- appending a board file would re-centre, but not re-zoom
Fixes: lp:1504302
* https://bugs.launchpad.net/kicad/+bug/1504302