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.
adding '$?' command to get position, spindle direciton/speed, feed and seek rate
creates global g_* variables in settings.c and updates them throughout rest of code

also, config.h pin change.  direction and step lines now next to each other
took out global position updates in planner and put it in stepper
grbl now has correct position querying
M30 minor bug fix.

Order of operations was off. Now works as intended,
Add support for overriding DEVICE and PROGRAMMER

By setting environment variables.

example: PROGRAMMER=-c arduino -P /dev/tty.usbmodemfa131 make flash