v1.0.3

Enter leaves a quote. A blockquote was a room with no door: every Enter
made another paragraph inside it, and the only way out was the mouse. Lists
have had the rule since splitListItem — an empty item means the writer is
finished — but the containers that are not lists never got it.
exitContainerOnEmpty puts the rule in one place, wired into blockquote
and callout, so a new container gets the behaviour by binding a key rather
than reimplementing the check. It fires only on a caret in an empty textblock
that is the last child, so Enter in the middle of a quote still splits and
Enter outside one is untouched.

autofocus: 'start' | 'end' does what it says. The option has been typed
that way since 1.0, but mount only checked truthiness, so both strings behaved
like true and the caret stayed wherever it already was.

Contact addresses moved to matrajs.com. amrela.co does not resolve, so
the address in the licence files — the one to write to about buying a licence
— had been bouncing.