Allow plugin to add flight modes to joystick button actions

Support up to 64 buttons, not limit to 16
Send a single button command and not a stream of commands at 25Hz
Send button commands through signals (it's coming from a different thread)
Hide gimbal support through analog channels (there are no MAVLink messages to handle it)

Map gimbal controls
Keep track of gimbal position within Vehicle

Add gimbal to external control signal

Add camera trigger
Add video start/stop/toggle recording
Add gimbal pitch and yaw

Fix debug output

When starting up, if you start the GS before connecting the bluetooth joystick the QGC needs to be closed and restarted to get it to recognize the joystick

Default to ThrottleModeDownZero

When starting up, if you start the GS before connecting the bluetooth joystick the QGC needs to be closed and restarted to get it to recognize the joystick

Add note about button bits

This reverts commit c01ceadd.

Don't send button pressed bits to MANUAL_CONTROL

Remove deprecated button count testing

Remove the concept of reserved buttons for manual control

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Some digital joysticks have already this correction
Add habilit to add or removecircle correction
Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>