Feature Request: Split into Server and Clients

[SPauly]

The Library Management System should be split into a server that enables multiple clients to communicate to it. Checklist:

• Create communication protocol (maybe enum classes for the header consisting of usertype, UID, kind of request followed by the message body)
• Create a client, that handles message parsing
• Create a new server interface to parse incoming messages and do some logging
• enable TCP ports and multi-threading