[mojosetup] New install for Mega-Glest fails on older Ubuntu

[Ryan C. Gordon]

> Looking at the code it seems only Zip archives can be glued to the mojosetup binary
> to get a working installer.

Yes. Zip files put some bytes at the end to tell you where they start, 
so you can find the start of a zip file, when it's at some arbitrary 
byte offset in the file. It's possible that .rar and .7z do this too (I 
haven't checked), but they aren't implemented yet.

.tar.bz2 doesn't offer this, and you don't want to use them in this way 
anyhow, as they can't support random file access (we'd have to walk the 
whole archive for each file we want to open in it. It can work, but it 
will be slow).

If the concern is compression, it's not unreasonable to put a tar.bz2 as 
an uncompressed .zip file entry. Installer unpacks the tar.bz2 when 
installing, but uses the .zip as basic metadata to find what it needs.

--ryan.