Plane: fixed build with OBC failsafe
AC_Fence: remove unused gps pointer
AP_Math: use const references not pointers for location functions

this makes life a bit easier for the new AP_Mission library

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_Limits: fix for new AP_Math API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_L1_Control: fix for new AP_Math API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_InertialNav: fix for new AP_Math API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_Camera: fix for new AP_Math API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_AHRS: use const reference not pointers for locations

this makes life easier for the new AP_Mission library

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
Rover: fixes for new AP_Math location API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
Copter: fix longitude_scale() call for new API

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
Copter: use const references for Vector3f parameters

this is more efficient than passing a whole structure on the stack

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
Plane: fixes for updated AP_Math and AHRS APIs

Pair-Programmed-With: Brandon Jones <brnjones@gmail.com>
AP_Mission: Library to handle auto missions and waypoints

AP_Mission: Fixed parameter naming.
Plane: integration with AP_Mission
AP_Mission: Addition of function to return home altitude only.
Plane: Removal of leftover g.command_total variables, transitioned to AP_Mission, mission.command_total()
Plane: When out of commands, transition to RTL, rather than staying in a redundant "RTL-like" state, auto with waypoint 0 as the active waypoint.  This simplifies the user interface, as there is only 1 RTL state.
Plane: Transitioned storage of home location to AP_Mission
Plane: Removed unused home_is_set variable.
AP_Mission: The old command_index() is now called waypoint_index().  Command_index() now returns the current "non-nav command"