Add WOU_PROTOCOL description to ar-usb/
Update INI and HAL configs for miller machine
Support AXIS_S for .INI file
WIP: synchronized rigid tapping
WIP: add kinematics/miller_kins.c for sync-spindle-motion
Merge branch 'develop' into feature/usb-rigid-tap
Merge branch 'develop' into feature/usb-rigid-tap
Merge remote-tracking branch 'origin/develop' into feature/usb-rigid-tap
WIP: update miller configs for synchronous spindle setting
Merge remote-tracking branch 'origin/develop' into feature/usb-rigid-tap
BUGFIX to HAL Comp Generator -- comp.g

* initialize __comp_inst at export() so that the other funcitons
  could use exported HAL signals
Add HAL component -- spindle.comp
Add testing nc_files for araisrobo/miller machine
Testing file for rigid-tapping -- nc_files/araisrobo/rigid_tap.ngc
WIP: connect emcmotStatus->spindleSync to spindle-velocity-mode
Release candidate for usb-rigid-tapping

* RIGID_TAP of emccanon.cc: prepare spindle velocity, accel, and jerk
* tpAddRigidTap of tp.c: prepare tc for TAPPING and REVERSING
* tcGetPosReal of tc.c: calculate xyz position based on spindle progress
* control.c, motion.c: prepare HAL signals to interconnect with spindle.comp
* spindle.comp: spindle component that takes velocity and position commands
* configs/araisrobo/miller: 3 axes milling machine for usb-rigid-tapping
Update miller settings at configs/araisrobo/miller
Update HAL for configs/araisrobo/miller
tp.c: force updating motion.spindle-velocity-mode while tp is IDLE
Add testing config, .test.ini, for araisrobo/miller