v1.1e: New laser features. G-code parser refactoring. CoreXY homing fix.

- Increment to v1.1e due to new laser features.

- After several discussions with some prominent laser people, a few
tweaks to the new laser mode has been installed.

- LASER: M3 behaves in a constant power mode.

- LASER: M4 behaves in a dynamic power mode, where the laser power is
automatically adjusted based on how fast Grbl is moving relative to the
programmed feed rate. This is the same as the  CONSTANT_POWER_PER_RATE
config.h option in the last version. NOTE: When not in motion in M4,
Grbl automatically turns off the laser. Again, it only operates while
moving!

- LASER: Only G1, G2, and G3 motion modes will turn on the laser. So,
this means that G0, G80 motion modes will always keep the laser
disabled. No matter if M3/M4 are active!

- LASER: A spindle stop override is automatically invoked when a laser
is put in a feed hold. This behavior may be disabled by a config.h
option.

- Lots of little tweaks to the g-code parser to help streamline it a
bit. It should no effect how it operates. Generally just added a parser
flag to track and execute certain scenarios a little more clearly.

- Jog motions now allow line numbers to be passed to it and will be
displayed in the status reports.

- Fixed a CoreXY homing bug.

- Fixed an issue when $13 is changed, WCO isn’t sent immediately.

- Altered how spindle PWM is set in the stepper ISR. Updated on a step
segment basis now. May need to change this back if there are any
oddities from doing this.

- Updated some documentation. Clarified why M0 no longer showing up in
$G and why a `1.` floating point values are shown with no decimals,
like so `1`.

grbl/gcode.h

@@ -145,7 +145,7 @@
 #define WORD_Z  12
 
 // Define g-code parser position updating flags
-#define GC_UPDATE_POS_TARGET   0
+#define GC_UPDATE_POS_TARGET   0 // Must be zero
 #define GC_UPDATE_POS_SYSTEM   1
 #define GC_UPDATE_POS_NONE     2
 
@@ -160,6 +160,15 @@
   #define GC_PROBE_CHECK_MODE   GC_UPDATE_POS_TARGET
 #endif
 
+// Define gcode parser flags for handling special cases.
+#define GC_PARSER_NONE                  0 // Must be zero.
+#define GC_PARSER_JOG_MOTION            bit(0)
+#define GC_PARSER_CHECK_MANTISSA        bit(1)
+#define GC_PARSER_ARC_IS_CLOCKWISE      bit(2)
+#define GC_PARSER_PROBE_IS_AWAY         bit(3)
+#define GC_PARSER_PROBE_IS_NO_ERROR     bit(4)
+#define GC_PARSER_LASER_FORCE_SYNC      bit(5)
+#define GC_PARSER_LASER_DISABLE         bit(6)
 
 
 // NOTE: When this struct is zeroed, the above defines set the defaults for the system.