Minimal thing to get working

DONE: finish summary store
DONE: move "sdk" bits over to "matrix" directory
DONE: add eventemitter
DONE: make sync work
DONE: store summaries
setup editorconfig
DONE: setup linting (also in editor)
DONE: store timeline
DONE: store state
make summary work better (name and joined/inviteCount doesn't seem to work well)
timeline doesn't seem to recover it's key well upon loading, the query in load seems to never yield an event in the persister
map DOMException to something better
- it's pretty opaque now when something idb related fails. DOMException has these fields: code: 0 message: "Key already exists in the object store." name: "ConstraintError"
emit events so we can start showing something on the screen maybe?
move session._rooms over to Map, so we can iterate over it, ...
build a very basic interface with
- a start/stop sync button
- a room list sorted alphabetically
- clicking on a room list, you see messages (userId -> body)