Fix more mention match cases for issue 46

Logging should warn failed typing notifs

Fix embeds not checking description value.

Add config option to specify default directory listing

This commit adds a new section and option in config.yaml for rooms and whether
they should be shown in the HS' public directory listing by default.

The default behavior is to show them.

Add config options to disable typing notifications and presence.

These are negative flags so that existing configurations can still work without modification. Otherwise the fields would be required and potentially break existing installs.