Expanded timeout clause syntax to support time-units.

condition-terminates-process Eric Lavigne lavigne.eric@gmail.com**20050824163858 handler-case added to spawn. Unhandled conditions signalled by a process will kill that process, rather than interrupting the entire lisp image. This provides a convenient way to kill processes, by signalling a condition. In later patches, the handler-case for may include code for sending termination messages to linked processes.