Fixes for bug #1274:

- Implemented calls on the form min|max(function returning multiple values),
  which may or may not be valid Modelica but which is used in Modelica.Math.
- Unified elabBuiltinMax and elabBuiltinMin, since they do the same thing
  anyway.
- Added Static.makeBuiltinCall, to make it easier to create builtin calls.
- Added fixed models to test case libaries/msl31/Modelica.Math.mos.


git-svn-id: https://openmodelica.org/svn/OpenModelica/trunk@6129 f25d12d1-65f4-0310-ae8a-bbce733d8d8e