derived: Added Flap Angle test for late offset

Should have added the test before changing the algorithm! Bad practice..
Flap Angle offset should not be changed unless really necessary.
EngOilPressFor20SecDuringCruiseMax is now for 60 seconds
Changes for the next release
Removed .dev tag preparing for release
Bump version: 0.18.1 → 0.18.2