Lot of refactoring for the future. CoreXY support.

- Rudimentary CoreXY kinematics support. Didn’t test, but homing and
feed holds should work. See config.h. Please report successes and
issues as we find bugs.

- G40 (disable cutter comp) is now “supported”. Meaning that Grbl will
no longer issue an error when typically sent in g-code program header.

- Refactored coolant and spindle state setting into separate functions
for future features.

- Configuration option for fixing homing behavior when there are two
limit switches on the same axis sharing an input pin.

- Created a new “grbl.h” that will eventually be used as the main
include file for Grbl. Also will help simply uploading through the
Arduino IDE

- Separated out the alarms execution flags from the realtime (used be
called runtime) execution flag variable. Now reports exactly what
caused the alarm. Expandable for new alarms later on.

- Refactored the homing cycle to support CoreXY.

- Applied @EliteEng updates to Mega2560 support. Some pins were
reconfigured.

- Created a central step to position and vice versa function. Needed
for non-traditional cartesian machines. Should make it easier later.

- Removed the new CPU map for the Uno. No longer going to used. There
will be only one configuration to keep things uniform.

coolant_control.c

@@ -2,7 +2,7 @@
   coolant_control.c - coolant control methods
   Part of Grbl v0.9
 
-  Copyright (c) 2012-2014 Sungeun K. Jeon
+  Copyright (c) 2012-2015 Sungeun K. Jeon
 
   Grbl is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -43,12 +43,8 @@ void coolant_stop()
 }
 
 
-void coolant_run(uint8_t mode)
+void coolant_set_state(uint8_t mode)
 {
-  if (sys.state == STATE_CHECK_MODE) { return; }
-
-  protocol_auto_cycle_start();   //temp fix for M8 lockup
-  protocol_buffer_synchronize(); // Ensure coolant turns on when specified in program.
   if (mode == COOLANT_FLOOD_ENABLE) {
     COOLANT_FLOOD_PORT |= (1 << COOLANT_FLOOD_BIT);
 
@@ -61,3 +57,11 @@ void coolant_run(uint8_t mode)
     coolant_stop();
   }
 }
+
+
+void coolant_run(uint8_t mode)
+{
+  if (sys.state == STATE_CHECK_MODE) { return; }
+  protocol_buffer_synchronize(); // Ensure coolant turns on when specified in program.  
+  coolant_set_state(mode);
+}