Converted Structure Scan to use CameraCalc such that it now works with
camera specs.

Change from BATT_VOLT_PIN to BATT2_VOLT_PIN.

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Also fixed bug with ArduPilot guided waypoint write which would trash
existing mission.

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Handle survey mode state

Also hand carried text to speech changes from Stable to master. Plus
unit tests for that.

Need to hand carry some stuff from Stable to master in order to fix

Fix crash when adding second structure scan