Improving camera controls in "Map view"

[Winter]

After having spent a lot of time in the `/editor` mode I feel that the camera controls in that mode are in all ways superior to what is implemented in the "Map view".

First, the center point for Zooming in/out. The "Map view" uses the mouse position as a center (*à la* Photoshop?), whereas in `/editor` the center for zooming in and out is always the center of the screen. I found the `/editor` behavior more pleasant to use because it mirrors the way zooming in and out works in game. Not relying on the mouse position makes it more reliable.

Second, the scroll speed in "Map view" way too fast. `/editor` seams to have less than half of that speed, which makes it possible to look at the base while scrolling and and to reliably place ghosts while scrolling. Moving arbitrary fast in `/editor` is still possible by first zooming out, moving and then moving in.