Video flag for scheduled pages / bare schedule items

[stefanor]

Currently in pentabarf.xml, the <event> for non-talk schedule items contains the static:

<recording>
    <optout>false</optout>
    <license>{{ WAFER_VIDEO_LICENSE }}</license>
</recording>

We should have some way to control this, so that video systems don't have to do heuristics.

Maybe a "no-video" boolean on scheduleitems, that overrides the default?

[hodgestar]

Are ScheduleItems stable enough to attach this information to? I.e. would it be lost if an event was moved to a different slot?

[stefanor]

Hrm, probably a duplicate of #384, which I didn't find in my quick skim earlier.

[stefanor]

As you mentioned in #614, they probably aren't stable enough, but we could make them more stable.