Draft Trimex

Description
This tool trims/cuts and extends lines and polylines.

Usage

 * trimming or extending is decided automatically from the position of your mouse
 * if you move the mouse cursor over another object, the trim/extend operation will snap to that object or segment
 * pressing will constrain you to the segment currently being trimmed or extended
 * pressing will invert the order of the trimming
 * chamfer & fillet are still not supported but planned