Simple implementation anti-spam protection.

[MairwunNx]

Anti-spam chat protection.

Chat does not need much protection, just basic protection against a fool.

• implementation of checking for identical messages
• implementation of chat delay
• implementation of the prohibition of chat messages containing ip address or URL.

Also desirable to have permission for bypassing message checking:

• ess.chat.identicalmsg.bypass (canceled for implementation)
• ess.chat.chatdelay.bypass
• ess.chat.advertising.bypass