Realistic AI helicopters

[Airtrooper]

This has been mentioned before, but it would be great to have realistic AI helicopter (plus tilt-rotor and VTOL in general) instead of having to hack the fixed-wing AI methods to get something which is really not good.

In fact it would be great to see this as part of an AI overhaul (with improved "plumbing", terrain-hugging runways, operations from AI ships, etc. etc.).