Bug fixes, logging, # in-flight reqs tweak
Bug fixes, logging, # in-flight reqs tweak

- Make it all work at run-time
- Add helpful logging (how far along it has got)
- Up the # of in-flight requests to 50. On matrix.org with Freenode, this takes
  1m30s to process 12k rooms.

matrix-org/matrix-appservice-irc,matrix-org/matrix-appservice-irc,matrix-org/matrix-appservice-irc