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

Make combat nonblocking, make multiple queues for distinct operations

fix(core): remove a contract after timeout

Merge pull request #55 from Rutherther/feat/contracts

Add contract system

feat(game): split nostale apis into safe, unsafe, add contracts usage

feat(game): add event constraint for IEveryGameResponder Respond

feat(core): add basics of a contract system