INS: updated MPU6K_FILTER parameter description
Copter: remove old commented out code from setup.pde
Copter: bug fix for loiter target
AP_Navigation: added a navigation controller class

the new L1 controller will be a instance of this class. Other
navigation controllers can be added as additional instances

Pair-Programmed-With: Paul Riseborough <p_riseborough@live.com.au>
AP_Math: added Vector2f.angle()

useful for calculating the vector in polar coordinates
AP_Math: fixed grammar error
AP_Math: added RadiansToCentiDegrees and RADIUS_OF_EARTH
AP_Math: moved a lot of vector templates to cpp from .h

this reduces the code size quite a lot on AVR
AP_AHRS: added wind_correct_bearing() and groundspeed_vector()

these are very useful for navigation libraries
AP_AHRS: fixed functions that need to be virtual

functions overridden in a child class need to be marked virtual, or
you get the parent class function
Addition of a first order complementary filter to AP_AHRS::groundspeed_vector
I have been unable to compile due to problems with compiling this branch
AP_AHRS:compile errors on complementary filter patch

Addition of a complementary filter to estimation of the ground velocity vector for use by the L1-nav
AP_AHRS::groundspeed_vector

Cleanup and parameter adjustment
AHRS: change time constants in complimentary filter

this handles GPS lag a little better
AP_AHRS

Added ground velocity complementary filter beta coefficient as an adjustable parameter
to help with flight tuning.
AP_AHRS

Changed default complementary filter coefficient from 0.05 to 0.1 based on flight test results conducted using a UBlox LEA-6
AP_AHRS: cleanup formatting of groundspeed_vector()

Pair-Programmed-With: Paul Riseborough <p_riseborough@live.com.au>
AP_L1_Control: Addition of library for geometry calculations required for L1 Control.

calc_L1_circ: generates L1 reference point on circle
calc_L1_line: generates L1 reference point on line
Plane: Integration of L1_Control for straight line and circular navigation.  L1_Control is a non-linear navigation controller that does not require tuning and provides curved path following.

To enable L1_Control for loiter and straight line following add the following to your APM_Config.h:
#define L1_CONTROL ENABLED
#define L1_REFERENCE_LENGTH [length]
where [length] is a reference length in meters.  The smaller the value the higher gain.  Try 2*groundspeed.
L1_Control: Added support for turn direction. 1 for clockwise, -1 for counter-clockwise