Hello,
I'm doing some testing on this package, thanks for the great work. 👍

I wanted to share with you two possible denial of service.
Right now, anybody can open a connection and keep it for ever doing :

- Bad command ( commands that are not handle by the parse() function )
c.nbrErrors++ will be incremented but will never trigger a connection close()

- Speak Up (When command is empty)
A connection can stay open , sending empty commands for ever

In both cases, the attacker can open as many connection, send either "bad commands" not parsed. So , for example, 1 char, 2char, 3 char commands or just empty commands and will never reach any disconnect.

As a quick fix, I would suggest this to evaluate the c.nbrErrors counter and disconnect if > 3
In both scenarios

Example:
File: conn.go
Line: 101

	if cmd == "" {
		c.nbrErrors++
		if c.nbrErrors > 3 {
			c.WriteResponse(500, EnhancedCode{5, 5, 2}, "Too many errors")
			c.Close()
		}	
		c.WriteResponse(500, EnhancedCode{5, 5, 2}, "Speak up")
		return
	}

file: server.go
Line: 137

	if err != nil {
		c.nbrErrors++
		if c.nbrErrors > 3 {
			c.WriteResponse(500, EnhancedCode{5, 5, 2}, "Too many errors")
			c.Close()
		}					
	
		c.WriteResponse(501, EnhancedCode{5, 5, 2}, "Bad command")
		continue
	}	

Hope this help.