T-only lines were not properly parsed. Should now be fixed to
be associated to currently selected extruder. Also added unit
tests for the temperature parsing.
While at it also extracted regexes and added unit tests for command
parsing (gcode & parameters)
Preprocessing for better performancy, unit tests for preprocessing, controls don't need a type anymore (makes things way less complicated and repetitive)
Refactored some things in octoprint.util.comm and octoprint.settings, added migration function to get users of the devel version up to date with their gcode scripts. Migration function will be removed again one week from now.
