Alternative renderers

[ralsina]

I have implemented a couple of alternative renderers, specifically:

• markdown -> terminal
• markdown -> markdown

I have code that should make it trivial to write a couple more (PNG and SVG) and I have "plans" for a PDF renderer (that supports HTML, will be fun!).

Those are currently in my markterm project. Would there be interest in adding them to markd itself?

Pros:

• Having more than one renderer in core helps abstract the base renderer at the proper level
• Maybe someone needs them (unlikely)

Cons:

• Makes markd larger and it's not like there's an abundance of person-power
• Makes advancing the HTML renderer harder