Speaker Check-in shows speaker who have no scheduled talks

[MacLemon]

This is a tightly coupled bug report and and a feature request. Sorry for my inability to properly separate the two.

Current Behavior

The speaker check-in page shows all speakers who have submitted a talk. Including those with non-scheduled talks.

Expected Behavior

The check-in page should group unscheduled speakers at the bottom of the list, or not show them at all.

Their arrival on site is not immediately important for running the event programme, but it still may be of importance to know for other reasons.

Suggested improved list could look like:

Speakers for today, sorted by time of appearance in the schedule, with room info where and when they're scheduled. Mark immedately/soon-ish required speakers who haven't arrived yet with a warning.
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Other speakers during the conference who have or have not checked in yet in alphabetical order.
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Speakers without scheduled talks

Steps to Reproduce

1. See Speaker check in list.
2. See speakers without talks

Context

We do Speaker Check-in at the Infodesk, because this is where pretty much everyone passes by as they arrive. Infodesk people mark speakers as arrived.
When the list is quite long, it gets hard to keep an overview who is here and who is not and action is required. (80+ speaker's is quite common for our events)

Would be helpful to narrow the list down to people who actually do speak. (Bug)
Would be helpful to structure the list to make it easier to immediately find speakers who arrive just-in-time for their talk. (Today list, more a feature request.)

This is on-site experience from PrivacyWeek and BSidesVienna.

Your Environment

• Version used: pretalx 1.1.2
• Environment name and version (e.g. Chrome 39, python 3.5): Chromium (more or less current version, doesn't matter)
• Operating System and version (desktop or mobile): macOS, Linux
• Link to your instance, if in production: https://conference.c3w.at/