Reduce console log spam (#3896)
* Reduce console log spam
A couple of different things:
* Increase the `MaxListeners` setting on `MatrixClient` and `Thread`, so that
we don't get "possible EventEmitter leak" warnings
* Disable a couple of warnings/info lines that are just part of regular
operation and are logged in large volumes.
* another noisy log line
* Reinstate warning about receipts for missing events
Apparently this is being worked on
