Startup at the user's location

[jidanni]

When we first use the editor, it is centered at
30, 0
Perhaps have it centered instead, at the location the browser says the user is at.

[jidanni]

You see, the user's first impression is that he is currently looking at the vast featureless desert located at 30,0,
and that is why the big map at the left is all blank:

[jidanni]

He then attempts to see his own location, as in #53.