Distributed database

[dbosk]

I like to have my material together. For instance, I have the course divided into modules. When I create questions for the exam related to a module, I'd like to store those questions in the module. So, if the module is included somewhere else, the questions (and statistics) are there.

This means that the exam is generated from questions from many places. See this Makefile for an example.

This issue is to some extent related to #27.