UITextView uses TextKit internally, unlike UILabel, so no additional
code is needed to keep the TextKit and view representations of the text
in sync since they are one and the same. This means that detecting which
character was tapped in a content text view is much more accurate, which
means link handling is substantially imrpoved.
Fixes#20
Also, copy the state between screens, so e.g. expanding a status in the
timeline and then opening that conversation already has that status
expanded.
This intentionally doesn't store the sensitive attachment visibility
state, since showing text when not necessary is less dangerous than for
images. (Possibly a preference for this in the future?)
Closes#55
Shadowfacts