Slide and subslide behavior

[jangenoe]

This is a great extension. I would love to use it while teaching. But at present, moving through the slides does not yet exactly behave as expected.

Description

In "Deck mode", right and down arrow keys (and the corresponding clicks on the navigator) seem to have the same behavior. Both go to the next cell. Correspondingly, the left and up arrow keys go the the previous cell.

Expected behavior

My gut feeling is to expect a behavior as the default Navigation Mode behavior in reveal.js Navigation Mode

• Left/right arrow keys step between horizontal slides (if the slide does not comprise fragments).
• Up/down arrow keys step between vertical slides (if the slide does not comprise fragments).
• Space key steps through all slides (both horizontal and vertical).
• Shift enter executes the cell and moves to the next cell.

Moreover, starting from a cell tagged skip (especially when it is the first slide)

"slideshow": {
        "slide_type": "skip"
    }

makes it difficult to proceed.