Editor, zoom isn't kept when changing topology (#234)

[Forestidia86]

This issue (#234) can really get grating when tailoring the map (zoomed out) to the wished size. It can take mutiple tries to get the proper map size and because of this issue one has to zoom out every time again to see if it fits.
The zoomed in map actually tells you very few about the full size of the map.

(I can see the use of automatically readjusting zoom when it is the default zoom.)

[Simon]

Right, resizing is highly disorienting and doesn't allow incremental adjustments.

In the long term, I want a better resizing dialog. And it would be really nice to focus the camera on the change.

Here's a short-term fix to ease the pain: When we resize the map in the editor, the camera will zoom out as far as necessary to view at least the entire map. This is usually as far out as possible.

This fix is alrleady on unstable's master branch. It's planned to go in the next release.

-- Simon