Validate all game inputs

[timotheeg]

The nestrischamps server right now is much too trusting on incoming game frames:

• binary messages are appended to game files regardless of their size and format
• if a non-supported version is received, the binary frame constructor can throw and crash the server

Expected

No user input should ever be able to crash the server. Replay game files should be of the correct format so they should protect themselves.

TODO:

Do minimum inspection on game frames before they are used for anything. No need to do full parsing of the data, but at least extract the version field and from it validate binary frame size

[timotheeg]

Done in https://github.com/timotheeg/nestrischamps/commit/00602042eb40a06eedd94b1cbc811ce730c9aad7

(alongside some other minor cleanups)