Prevent spamming

[pietertolsma]

Currently users can send around 5 messages per second and quickly disconnect and reconnect. This is a very vulnerable spot to hackers/spammers.

This issue is closely related to issue #1 and I believe that fixing this will also fix this issue. You need to find a way to set a cooldown on users, for example by setting a timestamp in the chatbacklog and checking when the last time was a user sent a message every time a user wants to send a new message. Also, there should be a client-side cooldown to prevent server overload (savvy hackers can of course overcome this, but we don't want to make it easy for them).

Setting a cooldown on reconnections is important as well. One way to do this is to track the IP's of clients and basically doing the same as with the chat messages.