This is a partial rework of Cossacs' camera gimbal software.
This patch adds LPF to airframe attitude used for camera stabilisation
and feed forward for camera actuators. Either of options can be
disabled on the compilation level to save flash and RAM if not
required.
Original Cossacs' code was optimized and code flow shortcuts were
added where applicable.
This patch is based on work of Crubier (LPF) and Cossacs (AxisLock mode).
I've just reworked it a bit by adding a dynamic memory allocation for
static module data.