No changes
#defines & #ifdef cleanup

Converted axis and tower indexes to symbolic names.
Converted boolean #ifdef's to #if's as needed
Used numeric boolean values in preprocessor per standard
Reduced ~5.4 k line buffer cache to ~1.4k, as it cannot ever
be the speed bottleneck. Reading new gcode lines is many times faster
than even the shortest possible physical move.
Merge pull request #263 from mrbi11/work092

Symbolic index names