add support for variable valve timing

[robingroppe]

Please consider implementation of variable valve timing. I would consider to go the same way as with ignition timing: simple 2d RPM vs. Centerline Deg for intake and exhaust cam.

[Jckf]

Variable valve timing is already supported, but only with a simple change-over at a certain RPM, not gradually over time or with multiple stages.

[robingroppe]

Ah okay, I am trying to mimic BMW M5x engines. Missing configs are VANOS and DISA.