* similar to http://www.vatsim.net/fp/
* own form, own widget class as a trial to further modularize GUI components
* removed all view models (now encapsulated)
* tweaked style sheet
* prepared for login/off sounds
* prepared for text message sounds
* helper method to play sounds
* enabled mute / mixer also in cockpit, including context menus
* settings for notification sounds
* some minor tweaks, e.g. changed signal/slot to C++ style where missing
* rename CStatusMessages to CStatusMessageList
* rename NetworkVatlib to CNetworkVatlib
* replace all occurrences of Realname with RealName (correct camel case)
* CSequence method corresponding to CList::append is push_back
* don't compile the qdbuscpp2xml metadata plugin by default
* CAircraftIcao string members always trimmed and capitalized
* added CComSystem::roundTo25KHz
* using epsilon comparison in a couple of places
refs #81