Prune redundant posts/render.go

[eddsalkield]

None of the functions in posts/render.go are ever used anywhere. By pruning this dead code, we lose the dependencies on github.com/microcosm-cc/bluemonday and github.com/writeas/saturday, aiding the packaging process.

Fixes issue #9.

[eddsalkield]

I initially introduced more commits than I intended in this PR. I've cleaned it up with a force push, and merged the branches to remove conflicts.

[thebaer]

Thanks for submitting this! While WF doesn't need these funcs, we do have some small proprietary web apps that rely on it right now. That might change in the future, but for now, we'll need to keep them in the library.

Since this is a breaking change, we'll slate this for v2.0 of the library and then we'll need to maintain a parallel v1.x track going forward, for apps that need the Markdown funcs. I've created a new branch for that, which we'll leave open in case any other changes are needed for it.

[eddsalkield]

That's great, thanks.

There might yet be more changes I'd like to make for code cleanup/packaging reasons, but once they're done can we consider cutting a 2.0.0 release for versioning reasons?

[thebaer]

Yep, that'll work great -- and then we'll just want to update WriteFreely to use v2.0.