Flush buffers on soft reset

Have soft reset flush buffers to clear pending commands, and free
controller up for new jobs.
Add G90.1 and G91.1 support to the visualizer.
Merge pull request #102 from michmerr/commandqueue

Flush buffers on soft reset
Fixing refresh.gif
Fixed negative remaining time bug. Closes #117
Merge branch 'gcode' of github.com:michmerr/Universal-G-Code-Sender into michmerr-gcode
Merge branch 'master' of https://github.com/winder/Universal-G-Code-Sender