Support for ranked voting

[horcsinbalint]

Support was requested on today's Választmányi ülés for ranked voting in General Assemblies.
The exact list of supported algorithms that we need to support will be selected by January the 31st.
The plan for implementing it: make it possible to give a ranking of people for the users, the rank would be compiled on the client side into JSON, sent to the server, which the server would validate, and save the result as a long question answer. After the end, the raw JSON data should be available as a separate endpoint to increase transparency (while maintaining anonymity), and the end results should also be shown in a human-readable way. The end result should be calculated using a well-established library (like julien-boudry/condorcet)