stepper: Initial commit of stepper test class

Signed-off-by: David Jander <djander@gmail.com>
stepper: Started writing Stepper and StepperCluster classes

Signed-off-by: David Jander <djander@gmail.com>
stepper: rewrite speed-based to steps-based

Implemented line drawing algorithm

Signed-off-by: David Jander <djander@gmail.com>
stepper: Implemented main loop and position callback

WIP

Signed-off-by: David Jander <djander@gmail.com>
Added move and gcode modules and converted stepper.py to cython


Signed-off-by: David Jander <djander@gmail.com>
Rewrote stepper.pyx in C and created new interface

WIP

Signed-off-by: David Jander <djander@gmail.com>
Fix typo

Signed-off-by: David Jander <djander@gmail.com>
audiodev.c: Added HW deinitialization, normalized speeds, lowered latency

Signed-off-by: David Jander <djander@gmail.com>
config.py: Corrected steps_per_mm and added sound_rate constant

Signed-off-by: David Jander <djander@gmail.com>
gcode.py: Implemented command generator

Signed-off-by: David Jander <djander@gmail.com>
stepper.py: Added new StepperCluster class as wrapper around audiostep

Signed-off-by: David Jander <djander@gmail.com>
GPIO: Added symlinks to gpio sysfs interface

Signed-off-by: David Jander <djander@gmail.com>
Merge https://github.com/yope/grunner