Added test for a loop with only DO in it.
Added test for a loop with UNTIL and  DO in it.
Added test for a loop with REPEAT and  DO in it.
Added test for a loop with WITH, REPEAT, and DO in it.
Define methods specialized to WITH-SUBCLAUSE.
Added test for a loop with INITIALLY, REPEAT, and DO in it.
Define method on PROLOGUE specialized to INITIAL-CLAUSE.