Add support for plugins: Phase II

[oubiwann]

I'd like to write a dragon plugin that adds Flickr images to blog posts (of a given size, arrangement, and link back to Flickr). There's a ticket for this here:

• Come up with an alternative to the Flickr image widget forgotten-roads/blog#82

In order to do this, though, I need to inject a task into the normal content-parsing workflow, before markdown is converted to HTML.

In order to that, I need Dragon to be event-driven (see #1). With that in place, adding plugin support should be pretty straight-forward.

Phase I Tasks (Milestone 0.5.0):

• See Add support for plugins: Phase I #2

Phase II Tasks:

• Add a plugin component
  • should include a plugin registry at the very least
• Identify existing ad-hoc content parsing/munging/hacking rules
  • separate these from existing, critical, general workflow
  • add them as new "plugins" (i.e., use the new data workflow API)
• Implement an initial plugin (e.g., Come up with an alternative to the Flickr image widget forgotten-roads/blog#82)

Phase III Tasks:

• See Add support for plugins: Phase III #44