Remove magic_string variable from Protocol::MessageHeader.
Add Element specialization for bool type.
Fix descriptor_source_modify().
Make MulticastService using DescriptorSource.
Small fix in descriptor_source_modify().
Service is now sending multicast "presence" messages.
Improve MulticastHeader, so it now handles magic_string.
Add Element specialization for char type.
Update code due to changes in MulticastHeader.
Port TcpService from GSocket to GSocketListener.
Add code initializing TcpService listening for a new connection.