This is used to provide menu entries that allows cancellation of
interactive drawing and routing tools without needing the keyboard.
It is provided in the drawing tools and the router tool.
The cancel event doesn't have any new functionality (e.g. track rip-up
for the PNS router - lp:1448460), this just adds it to the menu, where
it behaves the same as an Escape keypress.
This makes "rotate" into two separate TOOL_EVENTs, which each have a
"multiplier" parameter.
Also added is a namespace for 'free functions' that use TOOL_EVENT
public interfaces (perhaps with other inputs too) to centralise some
decision-making and calculations.
Fixes: lp:1660731
* https://bugs.launchpad.net/kicad/+bug/1660731
Seth Hillbrand
Jeff Young
Marvin Schmidt
John Beard