* disabled sets distance and max.aircraft to 0
* fixed changed snapshot detection
* added rendering enabled to signal, only one function to decide (instead of duplicated logic)
* fixed isCurrentThreadCreatingThread and renamed to isCurrentThreadObjectThread (this check was never working), added 2 more thread checks
* changed remove aircraft function to return number of returned aircraft (like with the containers this allows to avoid unnecessary signals)
* removed unused function ps_recalculateRenderedAircraft() / SimulatorCommon
* using Queued airspaceAircraftSnapshot signal for binding (functor connect does not provide connection type)
* extened ASSERTs to check threads
* simulator: initial situation function with return value (success?)
* simulator: avoid unneccessary copy and provide correct rendered flag in add aircraft function
* added unload function to disconnect signals / slots and simulator
* changed remote provider to return signal/slot connections to manually disconnect functor connects
* flag so pause can freeze or continue AI aircraft
* slightly changed unload behaviour in simulator context
Remark: Tested for FSX only
Solves #424 for FSX
* logical / physical add/remote member functions in drivers, renamed functions
* added access to snapshot
* snapshot generation in analyzer
* snapshot handling in driver
* moved simulator base class in own files (.h/.cpp)
* added functions as required to context
