Guidance_h earth commands and quaternion fixes/improvements

So now horizontal guidance returns commands in north/east earth frame and doesn't already rotate it to body frame. This allows for better handling of them in different controllers.

New and properly working transformations from earth commands to quaternions added.
No proper fixedpoint implementation so far... no change there compared to current master though. Should still be done for efficiency.

Tested the int_quat stablizitation with this in simulation and it works perfectly as expected.