Improved support for custom servo mixer, requires configurator update…

… as well.

Support for SyncPWM on simonk firmware.
Brushed motors PWM frequency is now in configurator GUI.

Improvements in servo mixer and GPS status; Update to latest configur…

…ator together with this firmware.

New stable version release; Addition of atail4 model; Fix for SBUS re…

…ceiver scaling; Spektrum satellite bind support; Fix in softserial code