Result pagination

[essepuntato]

Currently, RAMOSE does not implement the pagination of the results. While, in general, the current use of RAMOSE in the context of OpenCitations has not needed such functionality so far, it would be something helpful to have for possible extensions of the OpenCitations API, in particular when a lot of results are expected (e.g. if we want to return all the citations that go to all the articles included in a journal).

The pagination could be handled in different ways, but a reasonable one would be to connect it with a caching mechanism – see issue #15.