VFR HUD should be blue over brown - not green

#### Issue details
Virtually every artificial horizon indicator uses blue and brown (or orange-ish) for contrast, not green. It's an industry standard, and it's proven. The VFR HUD should follow the same standard.



In addition, the standard for roll indication is to hash the first two 10-degree increments and the third (30-degrees) would be a thick hash. Then you could remove more numbers from the HUD without sacrificing accuracy or clarity. Then the 45 and 60 marks should be thick hashes as well.

#### Version
All

#### Platform
[X] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

Start by locating the Mission Planner VFR HUD rendering entry point and inspect how the artificial horizon colors and roll indicators are drawn. Compare the current display with the requested blue/brown horizon and hash marks at 10, 20, 30, 45, and 60 degrees; it is done when the HUD matches those visual requirements on all platforms.

Written by the indexing model from the issue text.