When we draw a path, we usually want to close the path when clicking on
the end of another line. This uses grid helper to ensure this
progression happens as expected.
Distinguish between the snap-from and snap-to items. Previously, we
used the SELECTED or DRAGGED flags but the flagging arcitecture was
inherently fragile. This specifies items directly that should not be
used as snap targets.
Fixes: lp:1802795
* https://bugs.launchpad.net/kicad/+bug/1802795
Many items require precise, non-grid movement. Adding the ability to
flag a non-grid option will permit this behavior.
This is a required precursor commit to fixing lp:1738818 and lp:1771683
Seth Hillbrand
Tomasz Włostowski
Maciej Suminski