FIX: overlay offsets

[kierongreen]

Overlay offsets could be half a tile out on x and y coords due to calculations not matching that for ground and things. Showed at 4/3 zoom on my system but would depend on window size.

[prissi]

Thanks. I think you should also get SVN access ...

[kierongreen]

You know what happened last time I had that!

Although I wonder whether it should be width or height in general for this (or if it could be removed completely as it is just ANDed with 1)?

[prissi]

You never had used it, at least according to svn log. (Was is the thing with import instead commit? Do not worry so much anymore about that ... is was in revision 176 or so!)

[kierongreen]

Yes it was the import instead of commit. Have to say after that I was too afraid to put anything in!