Plugin SPI for pegdown

I'd be very interested in a plugin SPI for pegdown.

My particular use case is this.  Play framework currently uses markdown for all its documentation.  We'd like to pull all the code samples out of the documentation, and have them in Scala files that get compiled and tested, so as to ensure that our documentation always stays current.  The samples can be annotated with comments, and then referenced in the documentation, so when the documentation is compiled, it gets pulled in.  Akka does something very similar to this, but using RST.  We could move to RST, but that's a huge task, if we could stick with markdown, it would be much nicer.  This is probably not a feature that belongs in the core markdown library, but being able to plug it in would be very helpful.

I'll have a go at implementing this, but I'd like to get feedback here as to whether it would be something that would be accepted into pegdown.  I think it could be useful for more than just our use case.  It may even be a clean way forward to adding new features to the pegdown library itself.