Settings refactoring. Bug fixes. Misc new features.

This is likely the last major change to the v0.9 code base before push
to master. Only two minor things remain on the agenda (CoreXY support,
force clear EEPROM, and an extremely low federate bug).

- NEW! Grbl is now compile-able and may be flashed directly through the
Arduino IDE. Only minor changes were required for this compatibility.
See the Wiki to learn how to do it.

- New status reporting mask to turn on and off what Grbl sends back.
This includes machine coordinates, work coordinates, serial RX buffer
usage, and planner buffer usage. Expandable to more information on user
request, but that’s it for now.

- Settings have been completely renumbered to allow for future new
settings to be installed without having to constantly reshuffle and
renumber all of the settings every time.

- All settings masks have been standardized to mean bit 0 = X, bit 1 =
Y, and bit 2 = Z, to reduce confusion on how they work. The invert
masks used by the internal Grbl system were updated to accommodate this
change as well.

- New invert probe pin setting, which does what it sounds like.

- Fixed a probing cycle bug, where it would freeze intermittently, and
removed some redundant code.

- Homing may now be set to the origin wherever the limit switches are.
Traditionally machine coordinates should always be in negative space,
but when limit switches on are on the opposite side, the machine
coordinate would be set to -max_travel for the axis. Now you can always
make it [0,0,0] via a compile-time option in config.h. (Soft limits
routine was updated to account for this as well.)

 - Probe coordinate message immediately after a probing cycle may now
be turned off via a compile-time option in config.h. By default the
probing location is always reported.

- Reduced the N_ARC_CORRECTION default value to reflect the changes in
how circles are generated by an arc tolerance, rather than a fixed arc
segment setting.

- Increased the incoming line buffer limit from 70 to 80 characters.
Had some extra memory space to invest into this.

- Fixed a bug where tool number T was not being tracked and reported
correctly.

- Added a print free memory function for debugging purposes. Not used
otherwise.

- Realtime rate report should now work during feed holds, but it hasn’t
been tested yet.

- Updated the streaming scripts with MIT-license and added the simple
streaming to the main stream.py script to allow for settings to be sent.

- Some minor code refactoring to improve flash efficiency. Reduced the
flash by several hundred KB, which was re-invested in some of these new
features.
Added build info feedback in help

- `$I` prints the Grbl build info and version number. NOTE: `$I=xxx`
stores an additional 30 character string into EEPROM, which will be
printed with the build info the next time it’s run. This is for
identification purposes for users that have more than one system using
Grbl.
Compile in Atmel Studio fix.
Minor bug fixes.

- Bug fix for step and direction invert masks not immediately being in
effect. Now regenerates the masks when a user changes this setting.

- Bug fix for probing cycle. G-code standard mandates that there is an
error if the probe is already triggered when the cycle is commanded.
However, Grbl may have motions to pull off a previous probing cycle in
queue and can falsely lead to errors. To fix this, the triggered check
is performed within the probing cycle itself, right after the planner
buffer is synced. If there is an error, it will now alarm out as a
probe fail.
Probing cycle and view build info bug fixes.

- Probing cycle would drop into a QUEUED state, if multiple G38.2 are
sent. It would not honor the auto cycle start flags. To fix, the auto
cycle start state is saved at the beginning of the probing cycle and
restored at the end, since the feed hold it uses to stop a triggered
probe will disable the auto start flag. For now it’s a patch, rather
than a permanent fix.

- protocol_buffer_synchronize() also has a failure case. Auto cycle
start does not get executed when the system is waiting in here, so if
it’s in a QUEUED state already, it won’t resume. Patched here, but not
fully resolved.

- Fixed a problem with the “view build info” command. The EEPROM write
would do weird things and corrupt the EEPROM. Not sure exactly what
caused it, but it’s likely a compiler problem with an improperly
defined EEPROM address. It didn’t have enough room to store a full
string. To fix, the build info EEPROM range was increased and the max
number of STARTUP_BLOCKS was reduced to 2 from 3.

- Lastly, when a $I view build info is used for the first time, it
would normally show an EEPROM read error, since it wasn’t cleared or
wasn’t therein the first place. It will now not show that error. A
patch rather than a permanent fix again.
Fixed probe position sync error.

- Restored probe position syncing. Had removed a pull-off motion after
a probe cycle completes, but ended up de-synchronizing the g-code
parser and probing cycle positions. Putting the pull-off motion back
fixed the problem.
Allow '$$' in check mode.

- Now allows the ‘$$’ view Grbl settings while in check mode

- Updated the version build date
Fixed bug related to very very low feed rates.

- A very very low feed rate command like `G1 X100 F0.01`  would cause
some floating-point round-off error and freeze Grbl into an infinite
loop. To fix it, introduced a MINIMUM_FEED_RATE parameter in config.h
to ensure motions always complete.

- MINIMUM_FEED_RATE is set at 1.0 mm/min by default. It’s recommended
that no rates are below this value, but 0.1mm/min may be ok in some
situations.
Updated licensing
Moved Grbl Sim to its own repo.
XON/XOFF flow control variable typo.
G28/30 bug fix. Block '$$' during cycle. SO2 defaults.

- A G28/30 bug would cause it to move to machine coordinate [0,0,0] if
no axis words were sent. It was a typo in the new g-code parser. Fixed
and slightly re-written to be more consistent with the program flow.

- Updated the ShapeOko2 defaults based on testing on the real machine.
A little conservative, but it might change again after some more
testing.

- Now blocks ‘$$’ command during a motion, because the printout takes
too long and can starve the segment buffer.
Added EEPROM force clear.

- When updating from v0.8, the settings will wipe the startup lines and
build info locations so that it won’t use whatever is already there in
the EEPROM. Parameters (coord offsets) are retained. They should be ok
during an upgrade.
Turned off Sanguino
Merge commit '6af010fe6309a8b8304a5c0210e2ff2ec4171411' into dev

Conflicts:
	config.h
	report.c