mission dificulty option

make the main/sidemissions harder by using if Mission_Diff = 1; in the
Wasteland-config.sqf.
- change at mi48 AI heli's
- faster speed of missions
- front gunner AI present in boats
- tba - minefield arround abbondonned truck
raised chance on some missions for testing

love this new function, thanks @AgentREV
Merge pull request #31 from A3Wasteland/Mission_Difficultysetting

Mission difficultysetting