Missing types were handled by the superclass (in the case of zones)
PCB_CONNECTED_ITEM, which incorrectly returned "true" when testing lines
against zones.
Fixes: lp:1789195
* https://bugs.launchpad.net/kicad/+bug/1789195
... and GetMsgPanelInfo.
Step 4 in the g_UserUnit eradication effort.
Also removes a couple of conversion routines that were close
enough to extinction.
(cherry picked from commit c75da51)
Seth Hillbrand
Jeff Young
Tomasz Włostowski