- Fixed pausing fail near end of run bug.

 - Fixed pausing fail near end of run bug.
 - Show "Upgrading firmware" when upgrading.
 - Log excessive pwr communcation failures as errors.
 - Ensure we can still get out of non-idle cycles when there are errors.
 - Less frequent pwr variable updates.
 - Stop cancels seek and subsequent estop.
 - Fixed bug in AVR/Planner command synchronization.
 - Consistently display HOMMING state during homing operation.
 - Homing zeros axis global offset.
 - Added zero all button. #126
 - Separate "Auto" and "MDI" play/pause & stop buttons. #126
 - Moved home all button. #126
 - Display "Video camera not found." instead of broken image icon.
 - Show offset positions not absolute on LCD.
 - Dont change gcode lines while homing.
 - Dont change button states while homing.
 - Adding warning about power cyclying during an upgrade.
 - Reset planner on AVR errors.
 - Fixed pausing with short moves.
 - Corrected s-curve accel increasing jogging velocities.