Support for "Use compass" params

Plan: Mission loads from vehicle automatically

Rover fixes

Parameter loader fixes

- Cache only supported on PX4. Solo sends param updates at a high rate
to update gimbal values. This was causing the cache to update itself at
too high of a rate, killing performance, especially on iOS.
- Fixed read/write index usage to provide correct progress bar updates

They may show up after parameters ready is signaled. No way around this
since this is a protocol problem. So can’t test secondary component.

- Now responds to request_list using a worker routine to send out
params one at a time
- Support for failure modes for unit testing

Vehicle change: All items removed
Vehicle add: Request sync is not already in progress

* Qt5.5.1 link corrected.

* Qt5.5.1 tarball saves to project's root directory
since qt_deps_tarball used to have prefix of /vagrant.

* Add requests to update machine setup for both Travis and Vagrant

* Vagrant: use config variable in place of static string

* Vagrant: init and update submodules

Defer loading and binding of mission editing QML components

3.0 fixes

Removing duplicated QGCQGeoCoordinate

Don't show board orientation after compass cal

Disregard spurious MISSION_ITEM

Rework mission lines + various mission-related bug fixes

Fixes ardupilot abbreviations for #3588

Remove animation to save perf

Bump joystick settle constant