CHANGED: Cvpcb fpviewer and the pcbnew fpviewer no longer have an options dialog
ADDED: Add a side toolbar to the pcbnew footprint viewer (and the measure tool)
This also cleans up some of the settings structs in the viewers, since
it was somewhat confusing before.
Fixes https://gitlab.com/kicad/code/kicad/issues/2205
* Consolidate the measure tool into one tool (this gives cvpcb
unit changing and snapping capabilities in its measure tool)
* Transition cvpcb to use actions for the sketch modes
* Replumb how magnetic items settings are stored and used