* helper method to detect disconnected state
* clear ATC info if disconnected or not available
* unit test for "finders"
* added Doxygen file
* formatting frequency in text message tabs
* added to CVariant for value object
* signal in text message to indicate overlay messages
* info window component (currently not runtme aware, maybe changed in future)
* removed old window, adjusted GUI
* Cockpit, max frequency corrected to 136,975
* Text message components, tabs show cockpit frequencies
* fixed icons
* some aggresive sound for voice room joined/left, until full testing is complete