Revamped how the roster works. We're now using a channel to transmit snapshots of the roster, which is thread-safe. Also found and fixed a bug that was preventing new filters from being sent more than one stanza ever.

# Leave this file -- it activates the Mercurial EOL extension to
# convert newlines between various formats.
[patterns]
**.go = native
**Makefile* = LF
**README* = native
**.txt = native
.hgeol = native