Fix server bugs and refactor Javascript client

1. wsConnections.getConnectionById is deleted when resetting
   wsConnections to []. Move it to global.
2. Use WebSocketConnection.close instead of WebSocketConnection.drop to
   avoid error "Connection reset by peer" at the python client. Here
   update websocket package to 1.0.14 for additional close() parameters.
3. Return valid (0<=pos<169) positions in randIniPos()
AI can pass newly put bombs now