Allow variants

[raphink]

Use Case

When writing a course that could be taught on either one, two more days, it'd be useful to be able to tag slides with a variant and let showoff be started with a variant flag.

Describe the Solution You Would Like

Place one or more variant=<name> on slides to let Showoff filter out the slides (in a similar way to printonly/noprint, but more flexible).

Describe Alternatives You've Considered

I've considered using CSS for this and using display:none on classes that should not appear, but it results in white slides instead of removing them entirely.

[binford2k]

The way that I do this currently is by maintaining one-day.json and two-day.json metadata files and presenting with -f. Would this meet your needs?

[raphink]

I do that already for trainings where I include specific chapters, but for specific slides it forces to split the slides into separate files, which I find cumbersome (but maybe it's just me).