DEFINE-OPERATION now checks for the existence of TASK-INPUT classes when defining new operations.
TASK-INPUT now handles the different times.

As a result of the previous change, compilation of the
DEFINE-OPERATION form requires TASK-INPUT objects to exist. Thus any
DEFINE-TASK-INPUT forms need to be evaluated at compile time.

The resulting forms produced by DEFINE-OPERATION now contain
TASK-INPUT instances, thus a MAKE-LOAD-FORM is required so that these
forms can be compiled.