Port relevant parts of 9d4541c612 to glitch-soc

Port f7a6f9489d to glitch-soc

[API] [vanilla required] [glitch-soc optional] initial_state show_sensitive_media boolean changed to show_media string with options "default", "hide_all", "show_all"

Port 7901f9f63e to glitch-soc

Port the UI part of 76f3d5d16b to glitch-soc

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.)

* Refactor initial state: "me"

* remove "me" from reducers/meta.js