Revert 342d35a..d6b3217

This rolls back to commit 342d35a903ebff531d669ab555de1569fc0c1c2e.
Revert d6b3217..aa8d0ed

This rolls back to commit d6b3217420aec13f96a3004e2ab6fee7610d6962.
Merged hover only mode into obstacle avoidance code
Replaced the main hover code with the new code. Tested and works well.
New file is the code for rear and down facing sensors only