Enhancement Request: Allow for multiple tabs on the new calibration routines to accomondate different functions

[jharris1993]

IMHO, a serious limitation of the current "calibration" routine is that, though excellent, (thank you!), it is too limited as there are a number of things that can, and should, be included.  For example:

• Servo calibration constants. (Issue #296)
• Calibration "tweaks" for the motors so that straight-ahead travel is actually straight ahead.
• The ability to set the "warning/power-off" voltage levels to accommodate differing battery chemistries.
  • This could be implemented as a radio-button selector for Li-Ion/NiMH with the option to manually select the voltage(s). 
  • Note that this is actually worthy of its own issue as the hard-coded warning thresholds were designed for the NiMH battery pack and are totally unsuitable for the new LI-Ion batteries as the batteries die hard before the warning threshold is reached and the GoPiGo board "safety shuts down" the robot.  (See issue #311)

The basic idea is to design the calibration utility so that it can be expanded relatively easily with additional tabs for additional functionality that may be added in the future.