acceleration-Grbl now works with atmega 168 by disabling arc motion
fixed null pointer dereference in planner_forward_pass_kernel
fix sign of fractional part in printFloat
Reset the overflow flag to stop a queued overflow interrupt from resetting the step pulse right after sei() is called
Make sure we don't accelerate above the nominal_rate
Merge pull request #32 from jv4779/master

minor grbl code issues
Updated README and reordered branch versions.
Various minor updates and variable definition corrections. Removed deprecated acceleration manager.

- Removed deprecated acceleration manager (non-functional since v0.7b)
- Updated variable types and function headers. - Updated stepper
interrupt to ISR() from SIGNAL()+sei(). - General code cleanup.
Propagated premature step end bug fix from the edge branch. Updated printFloat() function.

- Will not be uploading a hex build of this, unless asked.
Merge chamnit/v0_7 with grbl/master
Merge pull request #47 from chamnit/v0_7

Merging chamnit/v0_7 to grbl/master
Update readme.textile
Updated streaming scripts. Compiler compatibility for _delay_ms().

- Moved obsolete streaming scripts to folder for reference.

- Added a more complex Python streaming script which uses the serial
buffer as an additional streaming buffer.

- Removed all references to a _delay_ms(variable) to allow for better
porting across different compilers.
printFloat rounding fix. Affected settings. Recommend using new build.

printFloat was printing incorrectly and adding a value of 5 to every
float instead of 0.0005 when rounding to 3 decimal places. The printed
settings values do not accurately portray the actual stored value.
Recommend using newly posted build.
Minor compiler compatibility update for _delay_us().
Fix to enable spindle DDR ports.
Homing search sequence now compile-time option. New defaults.h file. Tidying up.

- The homing sequence is now a compile-time option, where a user can
choose which axes(s) move in sequence during the search phase. Up to 3
sequences. Works with the locating phase and the pull-off maneuver.

- New defaults.h file to store user generated default settings for
different machines. Mainly to be used as a central repo, but each set
may be select to be compiled in as a config.h define.
Updated readme
Updated interface protocol. Fixed M2 bug.

- Updated interface protocol to play nicer with interface programs. All
Grbl responses beginning with '$' signifies a setting. Bracketed '[]'
responses are feedback messages containing either state, parameter, or
general messages. Chevron '<>' response are from the real-time status
messages, i.e. position.

- M2 Program end command was causing a system alarm. Fixed. Thanks
@blinkenlight !
Merge v0.8 edge to master