Make sure that cycle_start state is set before simulating steps.
Simplify setting of STATE_CYCLE and ISR interval.

Set sys.state to STATE_CYCLE directly instead of calling back to
st_wakeup().

Convert get_step_time() to a constant and rename it to ISR_INTERVAL.
Merge pull request #337 from michmerr/edge

Make sure that cycle_start state is set before simulating steps.
Added test g-code programs.
Merge branch 'dev' into edge

Conflicts:
	sim/simulator.c
	sim/simulator.h
Bug fixes for timers, added some wdt support for limit debounce.

- Typo in timer def,
- Handle 8 bit timers correctly,
- Don't skip TOP count in CTC mode
- added SREG for atomic bit operations
Restore changes made only for testing.
Merge pull request #441 from ashelly/edge-simfix

Fixes for simulator in alternate configurations.
Updated README
Updated README
Update README.md
Update README.md
Update README.md
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.
merge grbl/grbl/edge and mschorer/grbl/dev