- Changed code generation for when external object constructors are c…

…alled

  - It is now done after the input file has been read
  - Ext.objs can now depend on (fixed) parameters, including strings
- Added code to support string parameters
- Added testcase ExtObjStringParam.mos based on bug https://openmodelica.org:8443/cb/issue/1163


git-svn-id: https://openmodelica.org/svn/OpenModelica/trunk@5745 f25d12d1-65f4-0310-ae8a-bbce733d8d8e