Build standalone.
Dual compatibility with ioq3/openarena clients.
The pk3 filesystem keeps a handle open on each pk3 it sees, presumably to load
things fast. However, this easily exceeds the maximum number of open file
handles permitted by the system (which, at the time of testing, is 1024), so
adjust the code to open each pk3 on an as-needed basis and close it each time.
Reset to original default hunk size.
Reset default zone size.