Add support for link types

Hello Malecjan,

I think one can embed a graph in our notes using snippets


## This is my typical Note

It contains contents in standard Markdown and also snippets with graphs:

```Aspen
default Person, name
default_attribute Employer, company_name
reciprocal knows, is friends with

# Write out the narrative data
(Matt) [is friends with] (Brianna).
(Eliza) [knows] (Brianna).
(Matt) [is friends with] (Eliza).

(Matt) [works for] (Employer, UMass Boston).
\```

More content..

Then we can implement a processor of ‘graph snippets’. Implementation wise, for Aspen, I think this is to invoke their library to generate the corresponding Cypher…

… If we need the cipher we can process the markdown to extract it, or possibly other format. One could even have a universal graph model that helps to go from one format to another.

What uses do you foresee of Aspen? or Turtle embedded in markdown? (I’m curious :slight_smile: