Support batching terrain requests

Add support for HIGH_LATENCY2

Fix unit translators

* Flight modes still not implemented. Waiting on message change.
* Also includes various cauterization of UI things which should not be
available on high latency link.

It was broken when temperature translation was added in babbfbd1
The system wasn't quite setup to handle anything other than speed and distance. Changed so any arbitrary unit type can be converted to another.

Initial Corridor Scan support

initial Jenkinsfile OSX build configuration

Use runtime discovery of cpu core count

Float comparison to flakey cross-platform

Fix leaking QNetworkReply

Write only metadata

Move  MAV_PARAM_TYPE to  MAV_PARAM_EXT_TYPE as we're now using the proper MAVLink version.

Add gstreamer debug log option, and dot file output

Localization update

Fix NMEA settings layout

Insert ROI command which is supported by firmware

Structure Scan: Structure height support