This can result in less data to send to the cutter and faster engraving.

This makes generating large raster3d jobs much faster, with less memory
allocation and gc churn.

Add a configurable spindle value to use for 100% power. Marlin uses 100, others use 1.0, stock Grbl use 1000, some use 255.

Useful for saving to an usb-mounted smoothieboard or an sd card, instead
of manually saving to a fixed path each time.

Add configurable option to blank laser during G0 rapid moves. Fixes issues in PR #38 for Smoothie boards