triggered massive tweaking in physfs.c. A lot of code got little
cleanups, which was nice. Less malloc pressure, too, since opening a
file used to allocate a ton of crap and mush it together...now it's
basically down to one structure and the instance data in whatever
archiver.
which simplifies things, removes some responsibility and code
duplication from the archivers, and trims some malloc pressure.
Also ripped up the allocation hook code a little. We'll try to screw
with memory locking later, since it makes everything ugly and
complex. Oh well.