Add svg support for emus

Merge tedu upstream

skip over deleting old xonkers, we need to rethink this

if user is dead, save that

try assembling boxes async

actually not ready to cache nil

log box fetch failure, and cache result so as to not retry

fetch handles async

m

okay, don't delete old handles, since they're refetched interactively

fix some bugs in fetch tracker

Merge tedu upstream

clean up all the xonkers from time to time

fix mention fallback

small cleanup

Merge tedu upstream

try anchoring specific post in threads

another tune up for threadsort

save the fallback handle so we don't endlessly refetch

some threads may be getting large..