misleading comment in mapfile.h

[Frostregen]

The comment

"File offset to minimap (always 1024*1024 dxt1 compresed data with 9 mipmap sublevels)"

is misleading, because it is actually one 1024x1024 image plus 8 sublevels. (9 images in total)

I suggest to change it to:
"File offset to minimap (always 1024*1024 dxt1 compressed data plus 8 mipmap sublevels)"

Attached patchfile does this.
-Frostregen

[Kloot]

Done.

[Frostregen]

thx :)

(though "compresed" ist still spelled wrong )