undo some non working things
Revert "undo some non working things"

This reverts commit e10c75d29966ebf9c649589e917734910f83a39f.
Revert "a totally new take on altitude hold, safer yaw correction, i currently have concerns about pitch/roll integration"

This reverts commit 72d18917e2496c67f50c0db7bd1784adafcd640c.
sort out some bits
add compass (probably finished) and gps (not finished)
pretty sure that was invested!
calibrate gyro / z-accelerometer