v1.1d: Tweaked interface a bit. Added realtime spindle speed and build option data. Minor bug fixes.

- Increment to v1.1d due to interface tweaks.

- Based on GUI dev feedback, the toggle overrides report was removed
and replace with showing “accessory state”. This shows a character if a
particular accessory is enabled, like the spindle or flood coolant.
These can be directly altered by the toggle overrides, so when they
execute, a GUI will be able to observe the state altering as feedback.

- Altered the real-time feed rate to show real-time spindle speed as
well. It was an over-sight on my part. It’s needed because it’s hard to
know what the current spindle speed is when overrides are altering it.
Especially during something like a laser cutting job when its important
to know how spindle speed overrides are effecting things.

- Real-time spindle speed is not shown if VARIABLE_SPINDLE is disabled.
The old real-time feed rate data field will show instead.

- Compile-time option data is now included in another message
immediately following the build info version string, starting with
`[OPT:`. A character code follows the data type name with each
indicating a particular option enabled or disabled. This will help
immensely with debugging Grbl as well as help GUIs know exactly how
Grbl was compiled.

- These interface changes are detailed in the updated documentation.

- Reduced the default planner buffer size from 17 to 16. Needed to free
up some memory…

- For increasing the serial TX buffer size from 90 to 104 bytes. The
addition of real-time spindle speeds and accessory enable data required
a bigger buffer. This is to ensure Grbl is performing at optimal levels.

- Refactored parts of the spindle and coolant control code to make it
more consistent to each other and how it was called. It was a little
messy. The changes made it easier to track what each function call was
doing based on what was calling it.

- Created a couple of new get_state functions for the spindle and
coolant. These are called by the accessory state report to look
directly at the pin state, rather than track how it was set. This
guarantees that the state is reported correctly.

- Updated the g-code parser, parking motion, sleep mode, and spindle
stop calls to refactored spindle and coolant code.

- Added a compile-time option to enable homing individual axes, rather
than having only the main homing cycle. The actual use case for this is
pretty rare. It’s not recommended you enable this, unless you have a
specific application for it. Otherwise, just alter the homing cycle
itself.

- Refactored the printFloat() function to not show a decimal point if
there are no trailing values after it. For example, `1.` now shows `1`.

- Fixed an issue regarding spindle speed overrides no being applied to
blocks without motions.

- Removed the toggle_ovr_mask system variable and replaced with
spindle_stop_ovr system variable. Coolant toggles don’t need to be
tracked.

- Updated README

grbl/config.h

@@ -106,11 +106,23 @@
 #define HOMING_CYCLE_1 ((1<<X_AXIS)|(1<<Y_AXIS))  // OPTIONAL: Then move X,Y at the same time.
 // #define HOMING_CYCLE_2                         // OPTIONAL: Uncomment and add axes mask to enable
 
+// NOTE: The following are two examples to setup homing for 2-axis machines.
+// #define HOMING_CYCLE_0 ((1<<X_AXIS)|(1<<Y_AXIS))  // NOT COMPATIBLE WITH COREXY: Homes both X-Y in one cycle. 
+
+// #define HOMING_CYCLE_0 (1<<X_AXIS)  // COREXY COMPATIBLE: First home X
+// #define HOMING_CYCLE_1 (1<<Y_AXIS)  // COREXY COMPATIBLE: Then home Y
+
 // Number of homing cycles performed after when the machine initially jogs to limit switches.
 // This help in preventing overshoot and should improve repeatability. This value should be one or
 // greater.
 #define N_HOMING_LOCATE_CYCLE 1 // Integer (1-128)
 
+// Enables single axis homing commands. $HX, $HY, and $HZ for X, Y, and Z-axis homing. The full homing 
+// cycle is still invoked by the $H command. This is disabled by default. It's here only to address
+// users that need to switch between a two-axis and three-axis machine. This is actually very rare.
+// If you have a two-axis machine, DON'T USE THIS. Instead, just alter the homing cycle for two-axes.
+// #define HOMING_SINGLE_AXIS_COMMANDS // Default disabled. Uncomment to enable.
+
 // After homing, Grbl will set by default the entire machine space into negative space, as is typical
 // for professional CNC machines, regardless of where the limit switches are located. Uncomment this
 // define to force Grbl to always set the machine origin at the homed location despite switch orientation.
@@ -262,7 +274,7 @@
 // situation demands it, but be aware GUIs may depend on this data. If disabled, it may not be compatible.
 #define REPORT_FIELD_BUFFER_STATE // Default enabled. Comment to disable.
 #define REPORT_FIELD_PIN_STATE // Default enabled. Comment to disable.
-#define REPORT_FIELD_CURRENT_RATE // Default enabled. Comment to disable.
+#define REPORT_FIELD_CURRENT_FEED_SPEED // Default enabled. Comment to disable.
 #define REPORT_FIELD_WORK_COORD_OFFSET // Default enabled. Comment to disable.
 #define REPORT_FIELD_OVERRIDES // Default enabled. Comment to disable.
 #define REPORT_FIELD_LINE_NUMBERS // Default enabled. Comment to disable.
@@ -420,7 +432,7 @@
 // available RAM, like when re-compiling for a Mega2560. Or decrease if the Arduino begins to
 // crash due to the lack of available RAM or if the CPU is having trouble keeping up with planning
 // new incoming motions as they are executed.
-// #define BLOCK_BUFFER_SIZE 17 // Uncomment to override default in planner.h.
+// #define BLOCK_BUFFER_SIZE 16 // Uncomment to override default in planner.h.
 
 // Governs the size of the intermediary step segment buffer between the step execution algorithm
 // and the planner blocks. Each segment is set of steps executed at a constant velocity over a
@@ -451,7 +463,7 @@
 // around 90-100 characters. As long as the serial TX buffer doesn't get continually maxed, Grbl
 // will continue operating efficiently. Size the TX buffer around the size of a worst-case report.
 // #define RX_BUFFER_SIZE 128 // (1-254) Uncomment to override defaults in serial.h
-// #define TX_BUFFER_SIZE 90  // (1-254)
+// #define TX_BUFFER_SIZE 100 // (1-254)
 
 // Configures the position after a probing cycle during Grbl's check mode. Disabled sets
 // the position to the probe target, when enabled sets the position to the start position.