[autotools] added functions to lib
[functions] do no add to lib unconditionally
* since buildtime is huge and the libdunepymor
  gets around 380MB we only add the functions to
  the lib if
    -DDUNE_PYMOR_FUNCTIONS_TO_LIB
  is defined
[operators] minor cleanup
* use DUNE_PYMOR_SSIZE_T, refs #8
some clean up
* removed some exception specifiers, refs #4
* use DUNE_PYMOR_SSIZE_T, refs #8
[example.stationarylinear] minor fix