This module reimplements Python's native threading module using Panda
threading constructs. It's designed as a drop-in replacement for the
threading module for code that works with Panda; it is necessary because
in some compilation models, Panda's threading constructs are
incompatible with the OS-provided threads used by Python's thread
module.
Unlike threading.py, this module is a more explicit implementation of
Python's threading model, designed to more precisely emulate Python's
standard threading semantics. In fact, this is a bald-face copy of
Python's threading module from Python 2.5, with a few lines at the top
to import Panda's thread reimplementation instead of the system thread
module, and so it is therefore layered on top of Panda's thread
implementation.