Delta calibration menu based on http://minow.blogspot.com/index.html#4918805519571907051
To test/enable, uncomment the #define DELTA_CALIBRATION_MENU in Configuration.h
Actual menu change. Moved menu logic to not be shown unless not currently printing. (untested but straight-forward, printer in a bad state currently)
Merge pull request #1266 from RobotCaleb/DeltaCalMenu

Delta manual calibration menu