Firmware Upgrade ui re-work, plus QGCComboBox work

Firmware progress

QGCComboBox initial implementation

Fix missing 5.3->5.4 updates

Fixed issue #1261

Added menu support to QGCButton

Also fixed a typo (copy/paste error) in the TCP link settings loading where it was using the UDP port as the default value instead of the TCP port.

Qml Test dialog theme selection support

Cleaning dangling links

Updated palette and QML Controls per ui discussion

Qt 5.4 Upgrade

Repaired overwriting current files for flight data log (fix #1241)

changed criticalMessageBoxOnMainThread(const QString& title, const QString& msg) to QGCMessageBox::warning

Adding TCP to the Link Configuration Manager

Remove disconnect/re-connect on too many link errors

Also fix problem with incorrect symbolic link to plugins