Brimg back the v4 features, drop the flawed HD arms

[noahwaldner]

The V4 is a stellar fram, great flight performance, very rigid, good compatibility

With the transition to the HD the improvements from v3 to v4 were lost again.

• Arms are wider again and have resonance
• The spacing from the front to the rear motors have a shorter spacing again -> More propwash

Can we please fix this and make a arm set wich is thinner (like the v4) (maybe thicker carbon for the crash-a-lot pilots)
This would improve the flight performance drasticly. If we make the arms slightly longer, so that a 5.55" prop radius would fit, we can get rid of most of the propwash.

@tbs-trappy @ps915