Allow plugin to validate parameter setting.

Don't allow "Take Photo" is status is not idle.
Handle In Progress response (basically, do nothing)
Request capture status when stopping video recording.

For whatever reason, showing the dialog through a function causes a crash in QML (undebugable--new word!)

This reverts commit 9f41c6ea.

This reverts commit 52160d80.

Internet available now has a signal

* Resume index adjust to previous coordinate command
* Takeoff always added to resume mission
* Remove camera id checks which are no longer part of spec
* Simplified de-dup logic

This way:
* GCS location is shown
* It follows same centering semantics of FlightMap
* Note: Vehicle is not shown

Instead of resetting all parameters when some parameter change, explicitly define list of parameters that must be requested when a given parameter change.

Retry requests for storage and capture info.

Removed guess work from what parameters must be refreshed/updated when some other parameter changes. Added a "reset" flag that indicates when a certain parameter changes, the list must be reloaded.
Don't send a signal when setting a fact if the new value is the same.