Camera improvements

[trethaller]

Grouping various camera-related issues here:

• - The Camera is not yet very practical. Users would like to directly move the camera with the viewport controls, using the viewport camera as preview
• - Camera navigation is a bit clumsy, and inconsistent between editors (prefab / l3d). Quoting @ncannasse " review camera movement entirely (wrt zoom / translation) - base on looking at object (ray cast)".
• - Bug: changing animation speed also change camera movement (speed = 0 -> can't move camera)
• - The ability to adjust FoV using Alt is not super practical: it's often changed by mistake, and we would rather control the FoV manually for a given project
• - It would be nice to be able to switch between perspective and top-down ortho view without losing the perspective camera
• - For Darksburg, users requested to use the "game camera" to preview levels, using same settings and controls, without having to launch the game

What else?

[ncannasse]

Last point I think works well by setting a custom camera to use the same view as ingame, and adding a GameController that allows you to scroll using the gamepad - that's what we used for WT. Also follows terrain elevation. Works best if the game actually uses this camera preset at runtime too.

[ncannasse]

Suggestion for top view : single click on the icon to move from current-view to current-view with top camera (don't change the target viewed object), double click for full reset at (0,0,0) + top view
(same for perspective view)