The function `do_anonymous` in `hektor.py` was dependant upon the iteration order of a dictionary being the same as the insertion order. This is an implementation detail of CPython3.6 and should not be relied upon.

from 'key previous identifier fullname'
to 'key;previous identifier;fullname'

* Also the command line options should now work as expected
* Added an identity converter that just outputs .json output.
  This allows to postprocess files that have already been created.
* Breaking changes to the data format: students is now a list
* Bump python version to 3.5 to support typing