add MyMath.scala
add OpOverload.scala
rename user-player-json to mini-server-json
rename mini-server-json to mini-rpg-json
add TcpServer.java
add MsgCodec.java
add MsgHandler
JsonMessage
add MsgRegistry.java
delete folder: up
depends on GSON
finish MsgCodec
add server.Main
rename Main to ServerApp
add ClientApp.java