Revision 3577

NKSP: Introducing variable return type for built-in functions.

* Changed method signature VMFunction::returnType() ->
  VMFunction::returnType(VMFnArgs* args) to allow built-in
  functions to proclaim a different result value type depending
  on the arguments to be passed to the function.

* Built-in script function abs() optionally accepts and returns
  real number.

* Built-in script functions min() and max() optionally accept
  real number arguments and return real number as result in that
  case.

* Added real number test cases for the built-in abs(), min() and
  max() functions.

* Bumped version (2.1.1.svn7).