Port 5131012505 to glitch

flavours/glitch/util/initial_state is used in places where we want to
exhibit different behavior based on user preferences.  This means that
it's used in places where no preference is defined, i.e. on an
unauthenticated access.  All values exported from that module must
therefore expect that case; previously, the max chars value didn't.

Addresses #306.

max_toot_chars is present in the root of the initial state object.
(Previously, we were trying to read it from the meta child object.)