Do not dynamic cast or de-reference QObject, since object is either in
destructor or may have already been destroyed.

New mavlink logging support

Plus change to use QGCFileDialog

Using QFileDialog directly on OS X can hang intermittently due to Qt
bug. QGCFileDialog works around this by not using the native dialogs.

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

Remove PIXHAWK specific board support

Destroyed signal must have been working incorrectly in the past.

- 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

- Also renamed QGCCore->QGCApplication to better reflect usage.
- New global qgcApp api to access main QHCApplication singleton

Make sure to no de-reference already deleted object

Also renamed from QGCSettingsWidget to SettingsDialog to better reflect
usage.

This avoids collision with main app SettingsDialog class

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.

Ensure that the show event handling of the op map widget only creates on...

Map widget: make all connections that might suffer from multiple connect logic issues unique, found by Nyaruko

Bug fixes

This way OS X correctly positioned menu items

Auto pilot plugin architecture

This allows you to filter the list of parameters the widget displays.

This allows you to determine if full parameter list is ready if you
missed the parameterListUpToDate signal.

Create master/slave relationship for styles