Merge pull request #60 from Rutherther/feat/combat-v1

Make combat nonblocking, make multiple queues for distinct operations

feat(core): add support for timeout moving to errors

fix(core): do not wait in case state was already reached

fix(core): register contract after first state was executed

Merge pull request #55 from Rutherther/feat/contracts

Add contract system

feat(game): add timeouts to contracts

feat(core): add basics of a contract system