Better feedback for command failures

Plan: Scroll list to current item

Minor things

Skip "non compliant" Qt libraries (for Mac OS App Store)

Fix GStreamer relocation for Mac OS release (installer) builds.

* appveyor install nsis from s3

* Pass YAML linting, pls work

* Simpler nsis download scheme

Fix RTL_LAND_DELAY usage

Fix noisy output

Better messaging for no airframe set

WiFi sensor cal

Mag cal fix

Update PX4 meta data

Show mavlink sequence number packet loss in UI

Turn screen sleep back on correctly

Reenable writing to stderr on *nix platforms for useful debugging

Better command failure output

Plan: Adjust "Change command" for better usability

Parameter save: Notify user on read/write failures after retries