GCS:Move telemetry iodevices to the TelemetryManager thread

This avoids threading issues
GCS:USB retry failed writes

This fixes some issues I was having with Quanton
GCS:rawhid.cpp fixed coding style issues
GCS:Moved movetothread from connectionmanager to serial plugin
GCS:MapLib set proxy to default application proxy
GCS:Add proxy settings to general settings ui
GCS:mainwindow set application proxy
Merge pull request #1165 from guilhermito/gcs_proxy_allow

Allow the use of network proxy throughout the GCS
Merge pull request #1159 from guilhermito/gcs_bugfixes

Gcs bugfixes
Merge pull request #1144 from guilhermito/uavtalk_session_manager_rebased

Provides something similar to session management to UAVTalk
AltitudeHold: tune the amount of tilt compensation

The existing code would still drop during forward flight,
because of the non-linearities of open loop ESCs. This
allows tuning the amount of tilt compensation.