Everything now uses modelService, but there are still one or two
minor teething problems to fix.

This breaks functionality whilst both events.rooms and modelService
are in use.

Prevent EventStreamService from knowing too much about the EventHandlerService by changing the contract to just be a single initialSync response callback. Leave it up the handler to deal with splitting out information from /initialSync.

room.html now displays messages from model-service. Add debugging fields. Hook up the room member *at the time* to the message so it can display the right historical member info.

Use a proper elastic directive to make the <textarea> resize dynamically.
Use an 'asjson' directive to turn an ngModel of a JSON object into a
formatted JSON string so it can be displayed on the textarea. Also, deep
copy the state events being displayed, else it actually alters the underlying
data structures when playing around with the JSON in the textarea!

Content displayed in a modal dialog. Currently only read-only.

This uses /\blocalpart\b|\bdisplayname\b/i which is overall a lot
better than before. This specifically gets @localpart references
which the bug was originally for.

Use floating-point rather than integer division to handle timeouts so that non-zero but sub-second waits don't collapse to zero

This allows images to be clicked by clicking on the edge with the bubble.
This is important since Redactions are only visible on the event info
screen.

Fix an off-by-one bug in presence event stream pagination; this might be responsible for any number of bug reports

Construct a source-specific 'SourcePaginationConfig' to pass into get_pagination_rows; meaning each source doesn't have to care about its own name any more

UI for redactions is now complete.

I think this is better than overriding the right-click contextual menu.
Currently clicking this button does nothing.

Added a small 10px buffer so if the list isn't quite at the bottom it
still actually scrolls.