Clean states, entities and tests using them

[effa]

The goal is to make the test easy to read and write. Consider some simple conventions for naming timed entities, e.g. students s1, tasks t1, task sessions ts1, world states w1 etc. Also consider some conventions for tying entities with a wold-time alternatives, e.g s1.1, s1.2 for time series and s1.2b., s1.2b.1 etc. for another (alternative) world). Any ideas how to make it as readable and maintainable as possible welcomed.

[effa]

Plus:

• consider creating state from a set of entities, sth. like create_state([‘t1’, ‘t2’, ‘s1’])
• make sure that web can inherits all tests