Remove PIXHAWK specific board support

This is the Pixhawk research board, not the PX4 production board.
Ensure that the show event handling of the op map widget only creates one connection
Merge pull request #989 from mavlink/mapfix

Ensure that the show event handling of the op map widget only creates on...
Link connect/disconnect only through LinkManager

Centralize all connecting and disconnecting of links through
LinkManager::[Connect|Disconnect]Link api. Connect/Disconnect no longer
allowed through LinkInterface. This allows creation of new
LinkManager::setConnections[Suspended|Allowed] methods to disallow
connections as needed.
Use new LinkManager::[connect|disconnect]Link api
Rename SettingsDialog->SerialSettingsDialog

This avoids collision with main app SettingsDialog class
New LinkManager::[connect|disconnect]Link usage
Use new parameter save location
Added saved file location, Flight Data logging

Also renamed from QGCSettingsWidget to SettingsDialog to better reflect
usage.
QObject::destroyed signal fix

Make sure to no de-reference already deleted object
Saved files location support

- Also renamed QGCCore->QGCApplication to better reflect usage.
- New global qgcApp api to access main QHCApplication singleton
Update for QGCCore->QGCApplication name change
New mavlink logging support

- Logging now always on to temp file
- User prompted to save temp file after disconnect
- Orphaned temp logs checked for on boot
- Logs saved to new save file location
- Log file starts/stops with first and last connnection
Fix UAS unit test

Destroyed signal must have been working incorrectly in the past.
Hotfix: Make XPlane 9 work in HIL
Remove old connect/disconnect API
Fix flaky cross-platform variadic connect
Use SLOT not SIGNAL
Merge pull request #977 from DonLakeFlyer/RemovePixhawkAutopilot

Remove PIXHAWK specific board support
Use new QGCFileDialog api

Using QFileDialog directly on OS X can hang intermittently due to Qt
bug.