Removed the sleep in waitForOk to keep the marlin buffer full.
Added a marlin gcode compatibility layer that changes some standar GCode
commands to adapt them for Marlin. For example, Marlin does not support the F command, but
you can  use G1 FXX instead. Another example, Marlin does not support G0 as a full speed move,
so now you can set up a G0 feed speed and use that speed for every G0 command, while maintainig the original feed speed for every other command.
This feature needs more coding and testing.