Changes in 1.2
~~~~~~~~~~~~~~

It has been pointed out to me that I forgot to specify the default rexx
extension of ".rexx".  Thus, scripts in the form of

	foo.rexx

would not be started unless you actually stated :REXX foo.rexx instead of
being able to use :REXX foo alone.

Also added a semaphore lock in the GetJobNum()/FreeJobNum() routines to
prevent the job table from possibly being clobbered by EndSystemJob()
getting called at the same time CyberCron was trying to start another job.