+ Major cleanups:
+ * Various internal cleanups and performance improvement
+ Simulations are expected to run up to twice faster or so
+ * Make Process.kill(process) an instance method, not a static one
+ * User processes are not java.lang.Thread subclasses.
+ This breaks the compatibility (sorry), but previous API was
+ brain-dead, making it impossible to have non-trivial
+ initializations in the process constructor.
+ * Require a full constructor per Process sub-class.
+ Kinda breaks the compatibility (sorry), but this allows a much more
+ efficient way to launch the processes at simulation startup.