Turboprop Flight Simulator

* Added 'Flare & Chaff Decoys' and 'Missiles Detector' features for some military aircraft.
* Added the 'Enemies' configuration in free-flight in 'Systems & Features'.
* Added fire, smoke, and explosions when aircraft crash or get destroyed.
* Added two secrets about gunships.
* Added the 'Spring Season'.
* Added the 'Contextual Shortcuts' UI buttons block.
* Fixes and others (see in-game FAQ for more info).