Add several new random test cases and correct problems found by the tests.

o Make vector type check cause an runtime exception if attempting to
  use a dynamically typed vector where statically typed one was
  expected. Better type checking should be added to the parser to warn
  or error at parse time. But the failure must be mandatory, common example
  is attempting to use an untyped vector in place of a string.
o Correct missing check if a for statement test is empty.
o Correct assignment of spill offset of class field elements.