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>