picoC: advanced navigation features and bugfixes

Now picoC can be used for autonomous navigation tasks. Switch to PH and modify the PathDesired object to fly wherever you want. The script can read sensors and decide what to do by itself (#1343).
If picoC doesn't respond on commands there was already a programmed timeout of 10s. Now the widget generates a message box to inform the user about a failed command (#1259).
Further the upper limit of the USART Baud rate is removed. This may be useful to generate patterns for WS2812 LEDs or other stuff.