Document the Profile system

Erikj spec changes

Currently, if you leave a room you still appear in the members list.
This is basically a bug with the current implementation/spec, rather
than something that should happen.

Add a keyword argument to get_json to avoid retrying on DNS failures. Rather than passing MatrixHttpClient.RETRY_DNS_LOOKUP_FAILURES as a fake query string parameter

Fix ncorrect ports in documentation and add notes on how generate-config also generates certs bound to whatever hostname you give with --generate-config.

SYN-87 #resolved

Split PlainHttpClient into separate clients for talking to Identity servers and talking to Capatcha servers

Update README setup instructions to be correct. Make synapse spit out explanatory note when generating config to tell people to look at it and customise it.

Make instructions synctl gives for generateing a config file actuall generate a config file. Also, make synctil run synapse correctly by invoking a module such that the path is correct to pull in other bits from the working directory rather than requiring them to be on the PYTHONPATH (which would lead to people being very confused when they edit source in the working directory and their changes do not take effect).

Continue moving content out of docs/model/presence into the main spec; delete model docs that are duplicated

SPEC-25 #comment I've added the details of what the server should do on
receipt of a redaction event. In reality it can do whatever it wants,
and its probably a reasonable implementation to flag it up to a server
admin for verification before actually redacting an event.

Move documented but-unimplemented 'presence idle times' into a new document to contain such features

Nuke the entire 'Typing Notifications' spec section given as they don't exist yet in the implementation

Annotate all the 'TODO' marks as relating to either the specification itself or the documentation thereof