ArduCopter - updated to firmware version to 2.5.2 to avoid confusion with post 2.5.1 versions posted to downloads area

add ardutracker support
add load/save setting in Tracker
move getserialports to serial class
hopefully fix dtr issue for good.

The simulator flies very badly when using the full acceleration
code. I don't yet know if this is a bug in the simulation or a problem
with AHRS not handling acceleration for multicopters.

For now set the acceleration to be half a 'pure gravity' acceleration
and half from the full 3D calculation.

this is equivalent to multiplying by m.transposed(), but is more
efficient

this re-works the multicopter simulator in terms of rotation matrices,
and adds full acceleration support, which means it will include linear
acceleration affects and centripetal acceleration

this is a python library for rotation matrices, following the
conventions in AP_Math

fix issue 573
fix issue 572
fix issue 571
fix issue 570
fix issue 564
fix issue 560
fix issue 555
fix issue 536
add CH6_LOITER_RATE_D
fix joystick axis 5-8 - can use joystick for camera pan/tilt

this means we only link this in once, rather than for every use of
matrix multiply, which saves us some flash space

We need to be careful not to put large pieces of code in template
headers, as if the operation is used a lot, it costs us a lot of code
space

we now use the declination for Canberra

this implements a much more accurate model of a compass using matrix
rotations, instead of trying to calculate components directly

ArduCopter - navigation - corrected comment in check_missed_wp function to clarify that you've passed the waypoint when the direction to the way point is more than 100 degrees off (not 10 degrees off) from your original bearing towards the waypoint

ArduCopter - Navigation.pde - corrected comment re wp_distance and get_distance to clarify that they are in cm (not meters!)

AC_PID - added more paranoid checking that imax is positive in constructor, operator() and load_gains methods

this allows us to use a tested and optimised rotation method

this is the core method used to update the DCM matrix with a gyro
vector. Moving it to AP_Math allows us to have a test for it

if someone tries to set a AP_Int16 to a value of 300000, they now get
32767 instead of -27678

thanks to Justin for the suggestion

thanks to Justin for the suggestion

this will allow us to have an overall board rotation plus a per-sensor
rotation