Changed host:get_peer() and added more wrappers

host:get_peer(index) now returns the specific peer at a given index and
not the n-th connected peer.

removed functions:
  host:connected_peer_count() (can be done manually)

added functions:
  host:compress_with_range_coder()
  peer:index()
	peer:state()
	peer:connect_id()

Conflicts:

	docs/index.md
fixed sending of unsequenced packages

There was a bug where packets that were supposed to be sent as unsequenced
were sent as reliable. This fix now properly handles sending of unsequenced
packets.
ignoring vim's temporary files
all exported host and peer functionsare now documented