Use standard Magnetize() to handle grid and magnetic pads.
Use the standard menu from PCB_TOOL. Delegating the menu to
the SELECTION_TOOL just caused grief.
Also brings clients (such as Position Relative To) into line,
and implements better Cancel behaviour.
Also improves visibility of modal status messages:
- moves Select Anchor message from status bar to popup
- moves Select Reference message from dialog to popup
Fixes: lp:1786727
* https://bugs.launchpad.net/kicad/+bug/1786727
1) hide the status popup when the dialog is brought up
2) forward events from the popup to the canvas so hotkeys work
3) make sure diff pair radius is always 100%
4) fix greyed-out Miter style label
5) make L a hotkey so it works before you start dragging
Fixes: lp:1545856
* https://bugs.launchpad.net/kicad/+bug/1545856
Jeff Young
Seth Hillbrand
Maciej Suminski