add keybinds for camera zoom or fov

[SylvanFranklin]

In the keybind resource struct it would be very handy to be able to manipulate the fov of the camera. It could allow for automatic fov adjustment to create the allusion of smoother movement if so desired, but also as a utility to allow users to see more of the scene. I know that this is very easy to achieve outside of this plugin, but it seem like such a common use case that it might be a good candidate for something to add.