[service] extract session retrieval from "task" closure The session was retrieved there because `set_cnxset` must be called in the same thread as the code using it. We now retrieve the session beforehand and explicitly call `set_cnxset`.

[cubicweb/doc] Add tutorial on data import in CubicWeb. This involves creating the "tutorials/dataimport" directory structure under "cubicweb/doc" and, inside the "dataimport" directory, putting several files: - a ResT file containing the tutorial *per se*; this tutorial addresses the following issues: * creating a CubicWeb schema for representing a given data set (here, the Diseasome RDF data, for illustration purposes); * parsing the data; * importing the data, by using several stores: + the ``RQLObjectStore``, ``NoHookRQLObjectStore`` and ``SQLGenObjectStore`` from the ``dataimport`` module in CubicWeb; + the ``MassiveObjectStore`` from the ``dataimport`` module in the ``dataio`` cube. The tutorial also provides timing benchmarks of the various stores. - a set of Python files illustrating the data import, in the context of Diseasome RDF data parsing: * a Diseasome RDF data parse module, * a Diseasome data import module, * a CubicWeb schema for representing Diseasome data.

[dataimport] Slight message modification in exception handling code.

[dataimport] Handle various data formats when creating buffers from data. :note: On the long run, this should be addressed before, when these data are created.

[dataimport] Add a ``flush`` method for all stores. For ``ObjectStore``, ``RQLObjectStore`` and ``NoHookRQLObjectStore`` the method tries to call the ``commit`` method. For ``SQLGenObjectStore``, the ``flush`` method is basically unchanged with respect to previous changesets.

[dataimport] Uniformize the API across the different stores. This is achieved by modifying the ``relate`` method so that it takes an extra ``**kwargs``. More specifically, ``SQLGenObjectStore``'s ``relate`` method needs the the type of the subject entity which is passed through ``**kwargs`` as the ``subjtype`` keyword argument. Actually, it is the ``add_relation`` method of the ``SQLGenObjectStore`` who needs this argument. However, as this method is not called directly (but via the ``relate`` method), the ``subjtype`` argument is passed to ``add_relation`` via ``relate``. The other stores' ``relate`` methods do not need this extra argument, hence for the other stores ``**kwargs`` is empty. In this manner, the API is unified across the different stores.

[data] Add a CSS for undo UI rendering The nesting of ordered list and unordered list was badly handled. This has gone unoticed becaused it was not used. But the undo feature use this markup to render the changesets. That's why this minor change to ths CSS is introduced.

[web/views] extract cube geocoding (closes #353000)

[c-c list] add an optional argument to the list command (closes #2709703) This optional argument allows to restrict listing to only a given type of items (cubes, instances, configurations).

default base-url now uses fdqn instead of hostname only (closes #2542815)

[editcontroller] a small debugging help (closes #2518980)

[doc] small doc improvement

[doc] fix Pyro url

[doc] fix Narval project url

[tutorial] minor documentation fixes