Merge pull request mavlink#2705 from DonLakeFlyer/SDCardDelay

SD card delay detection changes

Merge pull request mavlink#2703 from dogmaphobic/detectInstance

Detect running instance and prevent loading second instance.

Stable v2.8.0

Merge pull request mavlink#1778 from DonLakeFlyer/VehicleErrors

Show vehicle errors after parameters load

Stable V2.6

Merge pull request mavlink#1685 from DonLakeFlyer/Stable2.5.2

Switch to 2.5.2

Merge pull request mavlink#1680 from DonLakeFlyer/Stable2.5.1

Switch to Stable 2.5.1

Merge pull request mavlink#1662 from mavlink/hilfix

XPlane HIL interface: Fix link deletion logic so no QGC reboots are r…

Merge pull request mavlink#1419 from dagar/master

Ubuntu package

Updated README to include instructions for libstdc++