Add aim modifier. It lowers elevator strength to 30%

Add AH-6 Little Bird helicopter.

Helicopters now maintain altitude when uncontrolled.
Helicopters now snap to 0 degrees when leaving control and less than 10 degrees.

Fix pgup/pgdown bug, it now seems to work properly.
also remove accel trolling (it has fullfilled its purpose, didnt actually nerf it, just made it annoying).
Make 20mm-like projectiles from planes not damage shields.
adjust some ac-130 values.

some flinn stuff

bugfix

add doppler effect to plane effects

add more reload effects to planes

Some AI improvements, nerf ac130 explosion, from flinnshadow.

Add chinese translations , thanks SamZong
Add AI fixes, thanks Flinnshadow