Artifact 1.1 features

[vitiral]

I have come up with what I think is a pretty decent roadmap for "Artifact 1.1".

The next release of artifact will focus on making it more ergonomic and even
easier to write clear design documents that link to code.

This includes the following features, which are subject to change while 1.0
is still in development:

• #185 support markdown as a data format and make it the default in settings.toml after running art init. (If nothing is specified in settings.toml, .toml files will remain the default).
• #158 embed a graph description language (graphiz DOT) to create auto rendered graphs like this
• #186 link to code for sub-items in text using [[.subpart]]
• #188 support [[@ART-name]] for substituting just the link to the artifact. This support will integrate with sub-parts and the DOT graphs, as you could do a node like a -> {b [URL="[[@.subpart_b]]"]} and the graph would have a link to that code properly rendered.
• #189 allow TST to link directly to REQ to enable requirements based testing.
• #190 A possible re-licensing of the project to MIT + Apache 2.0

In addition, I will do a refactor of artifact's own design documents using the above features. The refactor should also include a design path forward for how the different components should end up fitting together to better support external tooling.

[vitiral]

done in 2.0