New class: TCPConnection

A new class is born.
As by now I have different classes using TCP-connection I have decided to take the bare connection-code and move it to its own class, TCPConnection.
This class now is used for generic TCP-connection, without any specific protocol.
The protocol is then either implemented in the script, or in a class that either uses TCPConnection or extends from it.
I have started porting my *Connection class to extend from this class and thus will soon release updates for those.