Gcode quality is much improved, update/fix of add_rotation

[johannesnoordanus]

GCODE is a modal language and requires only changes of coordinates, speed, power or laser mode to be emitted, this update reflects that. Quality of Gcode is much improved and adapted to the latest GRBL. Updated all test results and checked for correctness, tested (multiple) transformations and checked for correctness.

• added rapid_move (G0) and dynamic laser power mode (M4).
• fix of 'repr' and 'add_rotation' function Rotation must include a center. Verified that transformations work correct now. Note that elliptical arcs are applied correctly!

Documentation: Gcode: http://linuxcnc.org/docs/html/gcode/g-code.html              http://linuxcnc.org/docs/html/gcode/other-code.html#sec:set-feed-rate (Gcode parameters)              https://www.cnc4fun.com/wp-content/uploads/2019/12/Grbl-Commands-v1.1-2.pdf (grbl v1.1 commands) GRBL 1.1: https://github.com/gnea/grbl/releases laser mode: https://github.com/gnea/grbl/wiki/Grbl-v1.1-Laser-Mode