Actions and emotions name the character who performs them

Actions and emotions name the character who performs them (0.10.0) (#54)

* Actions and emotions name the character who performs them (0.10.0)

Action and Emotion gain character_id, as Dialogue already has speaker: an
action beat in a multi-character shot could not say whose it is, so
consumers had to guess from the description's wording. Optional and
recommended; None when no listed character performs the beat. Registered in
the field tiers, the field registry and the events pillar schema; the spec
appendix is regenerated (276 -> 278 fields).

* Lock the 0.10.0 version