Plane: fixed a potential numerical error close to waypoints
AC_PosControl: bug fix to vertical speed limit

Vehicle was not reaching target climb or descent rate because of
incorrectly defaulted acceleration
Copter: restore SITL to run at 100hz
AP_InertialNav: get_velocity_xy const
AP_Rally: Added one getter method and made a utility method public.
AP_Mission: added get_current_nav_index() function

this will return 0 when there is no current command, which is what is
expected in MAVLink when there is no mission

(it prevents the text to speech announcing "65 thousand 6 hundred and
thirty five", which is quite annoying!)
Plane: use get_current_nav_index()
Rover: use get_current_nav_index()
AC_PosControl: stop I term build-up when motors at max
AC_PosControl: add get_accel_z method
AC_WPNav: bug fix to limit target point from moving beyond leash

Also pull Z-axis acceleration from position controller instead of using
#define
AC_PosControl: bugfix for freezing I-term build-up
Copter: control_hybrid initial version
Copter: integrate skeleton Hybrid mode
Copter: add hybrid state struct, formatting changes
Copter: refactor and split out wind compensation
Copter: add Hybrid parameters
Copter: restructure hybrid into more states
Copter: add hybrid_mix_controls

Allow wind comp estimate to run when vehicle travelling up to 30cm/s
(was 10cm/s)
Copter: hybrid works for 100hz and 400hz