- MAG, HEADHOLD and HEADFREE without a magnetometer. default orientation is north. (based on this idea: http://www.multiwii.com/forum/viewtopic.php?f=8&t=5088)

git-svn-id: http://multiwii.googlecode.com/svn/trunk/MultiWii_shared@1684 02679b44-d973-9852-f2fa-63770883b36c