Added tagging and forwarding

[Makefile]
- added forward.[hc]

[channels.[hc]]
- fixed IP address magic in accept and recvfrom
- added tcp sender
- streamlined the acceptor
- split the send and receive buffer

[conf.[hc]]
- added a tag (max 15 characters + '\0')

[pbuffer.[hc]]
- reindented the code properly
- added extra helper functions

[tlv.[hc]]
- added some extra helpers
- extract the tag from the buffer