only set it from the cmdline (you now CAN set it from the cmdline BTW!),
it defaults to the current directory if you don't.
New cvar fs_sharepath. Defaults to fs_basepath->string and is changed in
the same manner. If you do change it, files in gamedirs under it will be
used first with basepath's files overriding them.
This allows you to keep your paks in a read-only location (cdrom or unix
/usr/share) and still be able to override those files and save configs.
Use commas, not spaces or quotes or anything---the function used to do the
parsing is ... unintelligent. ;> Something better than the current
method will appear when we migrate to a better cmdline parser.
