Python CTypes wrapper now better supports WIN32

- improved PATH handling: adding eudaq/bin to %PATH% on the fly if not present so
  that EUDAQ.dll can be found (without modifying the global PATH for all
  shells)
directory for CTest ref data can now be set on cmd

- use -DReferenceDataDir="[PATH" to set the directory on CMake configure
- now used by nightly CTest script
added nightly batch script for WIN32

- fixed emptying of binary dir in nightly cmake script
- added exit on error when loading library in python wrapper