Added a workaround to create Starfall data directory.
Fix case of data directory.

The E2 editor folds to lowercase, which breaks things if we use
titlecase on a case-sensitive system (i.e. Linux). Rather than
fight with them we'll just switch to lowercase. It never worked
on case-sensiteve systems, and case-insensitive systems won't
be affected by the change.
Re-enable JIT globally.

I'm not sure what Colonel is on about in #132; this doesn't seem to
break anything. It's possible Garry fixed something since he posted
that. If we do find an issue it should be solved by disabling JIT for
the affected function, not globally.