This is under the supposition that we can't set the column widths
on some Mac instances because the host controls haven't yet been
created. This is primarily conjecture based on looking at things
that have the *possibility* of going wrong. Why this only happens
in some installs is beyond me.
Fixes https://gitlab.com/kicad/code/kicad/issues/5479
1) Zero out selection in tree when canvas captures focus so that
save/save as actions will go to canvas, not tree item.
2) Make save do a save to schematic when the canvas symbol is from
the schematic.
3) Copy fields when doing a save to schematic (setting the lib part
doesn't update them on its own).
4) Remove no-longer-necessary calls to update schematic after
saving symbols (the schematic symbols are no longer hot-linked).
Fixes https://gitlab.com/kicad/code/kicad/issues/6763
Adds Cut/Copy/Paste and Revert for footprints; introduces a new
shared Revert Changes? dialog; hooks up Add Library for footprints,
standardizes the Save As terminology.
Jeff Young