The apply settings and push settings options now take account of the
validity of the global pad settings when deciding whether to show or
not.
Global pad push now requires a source pad and doesn't push from the
global pad setting when there is no selection.
The whole submenu is hidden when there are no enabled items.
Fixes: lp:1664016
* https://bugs.launchpad.net/kicad/+bug/1664016
Import becomes apply and export becomes copy.
The term "push" to apply settings globally has not been renamed.
Swap the order of the copy and apply in the context menu.
This implements the pad import/export to the board's master pad setting
in the GAL canvases.
Implemented as a new GAL tool: PAD_TOOL.
It uses the same dialog, which has been split out into its own files in
pcbnew/dialogs, rather than along with frame methods in
pcbnew/globaleditpad.cpp.
Fixes: lp:1619304
* https://bugs.launchpad.net/kicad/+bug/1619304