Consider making slidify pandoc-compatible

[ramnathv]

Pandoc parses a markdown document into slides using the following rules (as taken from http://goo.gl/4CVWO)

• A horizontal rule always starts a new slide.
• A header at the slide level always starts a new slide.
• Headers below the slide level in the hierarchy create headers within a slide.
• Headers above the slide level in the hierarchy create “title slides,” which just contain the section title and help to break the slide show into sections.
• A title page is constructed automatically from the document’s title block, if present. (In the case of beamer, this can be disabled by commenting out some lines in the default template.)

[ramnathv]

On a related note, there seem to be multiple approaches taken to separating slides in a markdown document

1. Most of the ruby based tools like showoff, keydown etc. seem to use !SLIDE foo bar to define a slide with class = "foo bar". Users can wrap the specification as <!SLIDE foo bar> so that the markdown document is rendered neatly, even as just a page. showoff has an extra feature thrown in that uses all <h1> tags as slide delimiters if it does not find any !SLIDE specification.
2. In the python world tools like landslide and hieroglyph seem to prefer --- as slide separator and using reSt directives to specify slide classes and transitions.

I need to think more about the pros and cons of each approach, and what I would like to use for slidify. It might be a nice idea to do a survey on what people think about these options, and if it is important at all.

I personally like the <!SLIDE foo bar #id> idea since it is clean and allows easy parsing of slide classes and content. The only problem is that it might be cumbersome to write, over --- which is easy.

[ramnathv]

Right now, I have implemented the following.

1. Preferred way to separate slides is to use !SLIDE foo bar or <!SLIDE foo bar>
2. If no !SLIDE tag is found, a helper function searches for --- and replaces it with !SLIDE before slidification.
3. If neither !SLIDE nor --- are found, then a helper function adds !SLIDE before ever ### heading.

I need to make this customizable, since different html frameworks use different default levels for slide titles.