MAJOR CHANGE, handle directories as PAKs

MAJOR CHANGE, handle directories as PAKs
this change lets one put extracted paks directly into the Paks/ dir.
the folder structure must look like this
Paks/
    Pack-Name/
             data/
                 ....
    Pack2/ ...
    another.pak
ATTENTION: to achieve this i have stripped off much legacy junk.
openbor now can't handle non-lowercase filenames anymore, and
.pak's are supposed to use a forward slash instead of backslashes
as path delimiters.
this means you can't directly play .pak files from some website.
old mods must be extracted once with the newest borpak,
then repacked, and then they're good to go.
this will convert the filenames into a sane format.
altho, why even put the mod in a pakfile ?
i find it much more convenient to have the paks in an extracted
form. additionally it is much faster, since filename lookups in
all major filesystems are heavily optimized.