Resolve "openFile of CST_MicrowaveStudio class should be a hidden method"

Closes #9 (closed)

Occurrences of openFile

cst_python_api\CST_MicrowaveStudio.py:
  41          
  42:         # If a folder and filename are specified, call the openFile method    
  43          elif folder != "" and filename != "":
  44:             self.openFile(folder, filename)
  45                  

  71      
  72:     def openFile(self, folder, filename):
  73          

  85              print("CPA: Trying to open specified project.")
  86:             self.__CST.OpenFile(fullPath)
  87              self.__MWS = self.__CST.Active3D()

tests\test_CST_MicrowaveStudio.py:
  46          - __init__()
  47:         - openFile(): Opening an already existent project.
  48          - quit()

  78          - __init__()
  79:         - openFile(): Opening a new project.
  80          - saveFile()