[AHRS/GPS] - Cleanup code

[heappy]

New Attitude algorithm was implemented. Hmc orientation corrected and tested (For hype with 45° angle positiv z direction (z down))

• Remove Magnetometer (hmc5883) from GPS worker
• Add source switch for magnetometer (actual selection via -DGPS_MAG within AHRS environment)
• Remove old Attitude algorithm from attitude estimation
• Add orientation addition for hype
• Remove current compensation from ahrs with external source