Clean up soundfield simulation related applications

Todo:

[ ] Increment version number to ensure setup is rerun to resolve path issues

Changes:

• putting all sound field simulation classes/files in one folder
  • Numeric
  • VirtualAcoustics/Raven
  • VirtualAcoustics/diffraction
• removing unsed applications/Numeric/SH folder
• moved IniConfig to external_packages
• clean up Raven folder
  • renamed load_ac3d to itaAc3dModel (backwards-compatible: load_ac3d now returns object of this class)
  • removed all xml related stuff (this can now be found in RAVEN-Installer)