ALL THE LINKS! Most APIs now link to relative paths off the doc, outlined at the bottom of the .rst.

More formatting, more TODOs. Settled on a way of linking to external API docs; started converting references to relative links.

spec: Added internal links to different sections. Added NOTE and WARNING admonitions and hide away loooong TODO lists behind comments. Smaller ones remain.

Little bit more on syncing APIs, need to know more about responses before more work can be done on it.

Rename 'state' presence key to the much more obvious 'presence'; maintain a legacy 'state' copy for now

Fleshed out joining/leaving rooms. Added M_LIMIT_EXCEEDED standard error code for rate limited requests.