Remove listeners from Effect, as globally unused.
Merge branch 'master' of https://github.com/nonokun/hstcg.git
Make listeners pure functions.
Remove no-op listeners.
Move listeners initialization into constructor.
Generate listeners addition in Minion Cards contructors.
Start considering the prototype to get the onDamageReceived listener.

There is an issue here. The onDamageReceived of prototypes is
immediately overriden by the "builtin/standard/required" one in Minion.
Apply Listener on an Object instead of an Entity.

This is sad from a typing point of view, but should be temporary and
will permit more flexibility in the short term.
Oops: Secret is no Entity, hence does not generate more possible Moves.
Merge branch 'master' of https://github.com/nonokun/hstcg.git