Added sanity check for missing classes after use base of the user's use_base list. This spots missing classes (i.e, ones that didn't compile) before their sub's fail up as "shellexec" calls at runtime.
Execution front end for schedules. Main use is tying together the various modules used with S::D for running a set of jobs. Exports "runsched" to pass in the schedule and optional sequence of schedule items to debug for #! code.