OBS Slideshow Convertor

[jag3773]

We need to revise and integrate the slideshow generator for OBS stories. For example, this is what we are replicating, https://unfoldingword.org/en/slides/360px/01/#/ .

There are two versions of this script, one at https://github.com/unfoldingWord-dev/tools/blob/master/obs/js/reveal_export.py and one at https://github.com/unfoldingWord/unfoldingWord.github.io/blob/develop/_plugins/language_slideshows/generate_script.py . The second was is the most recently used one for the uW website.

This is related to #74.

This should be part of the regular OBS to HTML generation. I'd suggest keeping the same directory layout, which has the slides in a slides/ sub directory. In fact, copying the existing slideshows over from their previous location works as expected.

Static files for the pages are in door43.org repo via #813 .