in most of files, including wx.h is not necessary, when only 2 or 3 wx files must be included.
Moreover, on windows, including wx.h sometimes create compil warnings about
shadowed vars defined in some specific windows headers.
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
Wayne Stambaugh
jean-pierre charras
Seth Hillbrand
Jeff Young
Seth Hillbrand
Maciej Suminski