Fixed "dirty/clean" functionality to work properly on all tabs,
including autogenerated ones.
Changed to using signal/slot approach, instead of directly calling the
setDirty method. This ensure that the calibration methods are independent
of the calling widget, which allows for easy reuse.
Fixed dirty/clean support in output tab.
Changes requested from review.
Add specific dirty check for PipX. The behavior is now:
1) if an autopilot is connected then all pages generate warnings
2) if a PipX but there is no autopilot connected, then only the PipX
   configuration tab generates unsaved warnings
3) if nothing is connected then no pages generate warnings.
Merge pull request #301 from kubark42/fix-missing-unsaved-settings-warning

GCS Output module asks to save changes when none are made