[freespace2] support for polish version of freespace 2

[Bradley Bell]

Quoting Taylor Richards <mtrs at bellsouth.net>:

> It's when it tries to parse the strings.tbl in localize.cpp (had this
> problem with FS1 at one time) it looks for the particular language.  It
> will search for the default (English/default) which may not exist in
> this particular table and will crash if the language is not specifically
> set in the ini file.  The German version will use German as default if
> the option does not exist.  Without looking at the table I'm guessing
> that it's layout is to blame.

I know it's sorta kludgey, but you could just check the md5sum, or the file size
of strings.tbl, or another file, and select the language based on that.  I know
there are a lot of versions to check against, but I don't think it would be an
excessive amount.  And it can always fall back on the compiled-in default or the
.ini setting.  But at least for most end-users, it would just be "automagic".

-brad