[Done] Option for Camera movement when mouse on window borders

[Omega]

^{As per https://forum.megaglest.org/index.php?topic=7477.0}

When you move the mouse to the borders of the game window, the camera will move in that direction. This is an intended behavior and many players will make use of it. However, some players have voiced that they would prefer to disable this feature (the camera can also be moved with the arrow keys, by default). An option, preferably in the INI and the options menu, that could toggle whether or not this behavior occurs would ensure everyone is happy. The current behavior should remain the default.

[John.d.h]

I'd certainly like to be able to disable it.  I only intentionally navigate with the arrow keys. :P

[silnarm]

What a simple change this would be, and how useful... that auto-scrolling at screen/window edge often annoys me.

Will do.

[Kiko]

I don't know what's being done to GAE-4 regarding this screen scrolling behaviour, but I find the mouse-at-edge scrolling perfect, and only use the cursor keys for finer control (though I've just found that I can set the scroll speed in the .ini file too).

One thing which is a bit of a pain is when I'm doing something else (phone call, etc) and inadvertently nudge the mouse, causing the screen to madly scroll in some random direction. Would it be possible to make it stop at the game edge or not work when paused?