Increment to v1.1a, minor compile bug fix, tweaked communication protocol, more docs.

- Incremented to v1.1a, rather than keep 1.0e. This is because there
are existing v1.0 installations. Don’t want to confuse people further.

- Certain version of the Arduino IDE did not like the `inline` in the
function header. Removed from spindle_control files to fix the problem.

- Tweaked the communication protocol slightly. Added message type
indicators for all `[]`bracketed feedback messages. It’s been
problematic for GUI dev to try to determine the context of a message
and how it should be handled. These indictors should help tremendously
to remove context all together.

- Also altered how `$N` startup lines are presented when executed. They
now start with an open chevron ‘>’ followed by the line and an ‘:ok’ to
indicate it executed. The ‘ok’ is on the same line intentionally so it
doesn’t mess up a streaming protocol counter.

- Managed to save a 100+KB from refactoring parts of report.c. (Thanks
Vasilis!) Freed up room to alter the protocol a little.

- Wrote a markdown document on interface messaging to make it clear how
it’s intended to work. See interface.md in /doc/markdown

- Started to pull in some Wiki pages from the old grbl site and
beginning to update them for v1.1.

- Created new commit log for v1.1.

grbl/print.h

@@ -46,7 +46,7 @@ void printFloat(float n, uint8_t decimal_places);
 //  - RPMValue: Handles spindle RPM values in settings and reports.
 void printFloat_CoordValue(float n);
 void printFloat_RateValue(float n);
-void printFloat_SettingValue(float n);
+// void printFloat_SettingValue(float n);
 void printFloat_RPMValue(float n);
 
 // Debug tool to print free memory in bytes at the called point. Not used otherwise.