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

README.md

@@ -7,7 +7,7 @@ _**This is the development branch for Grbl v1.1's upcoming release. Please keep
 
 ***
 
-Grbl is a no-compromise, high performance, low cost alternative to parallel-port-based motion control for CNC milling. This version of Grbl runs on an Arduino Uno.
+Grbl is a no-compromise, high performance, low cost alternative to parallel-port-based motion control for CNC milling. This version of Grbl runs on an Arduino with a 328p processor (Uno, Duemilanove, Nano, Micro, etc).
 
 The controller is written in highly optimized C utilizing every clever feature of the AVR-chips to achieve precise timing and asynchronous operation. It is able to maintain up to 30kHz of stable, jitter free control pulses.
 
@@ -42,7 +42,7 @@ Grbl includes full acceleration management with look ahead. That means the contr
 
 - **Sleep Mode** : Grbl may now be put to "sleep" via a `$SLP` command. This will disable everything, including the stepper drivers. Nice to have when you are leaving your machine unattended and want to power down everything automatically. Only a reset exits the sleep state.
 
-- **Significant Interface Improvements**: Just this one time and done simultaneously with adding override data and controls, Grbl has tweaked the communication interface to make it easier for developers to write and maintain their GUIs. _NOTE: GUIs need to specifically update their code to be compatible with v1.1 and later._
+- **Significant Interface Improvements**: Tweaked to increase overall performance, include lots more real-time data, and to simplify maintaining and writing GUIs. Based on direct feedback from multiple GUI developers and bench performance testing. _NOTE: GUIs need to specifically update their code to be compatible with v1.1 and later._
 
 	- **New Status Reports**: To account for the additional override data, status reports have been tweaked to cram more data into it, while still being smaller than before. Documentation is included, outlining how it has been changed. 
 	- **Improved Error/Alarm Feedback** : All Grbl error and alarm messages have been changed to providing a code. Each code is associated with a specific problem, so users will know exactly what is wrong without having to guess. Documentation and an easy to parse CSV is included in the repo.