lots and lots of bugfixes after running on reals hardware for the first time

gcode.h

@@ -28,6 +28,7 @@
 #define GCSTATUS_EXPECTED_COMMAND_LETTER 2
 #define GCSTATUS_UNSUPPORTED_STATEMENT 3
 #define GCSTATUS_MOTION_CONTROL_ERROR 4
+#define GCSTATUS_FLOATING_POINT_ERROR 5
 
 // Initialize the parser
 void gc_init();