Dishmint/issue24

[dishmint]

The parser is mostly just a converter from tokens to elements. It also parses delimited sequences.

[dishmint]

I use FixedPoint to repeatedly form delimited elements, and it seems to be going infinite atm, so this ticket is not yet resolved.

[dishmint]

Caught all the cases that were causing bugs so far. Now here's what I have left.

• [x] Token to element conversion
• [x] Delimiter Parser
• [x] Test on full markdown file (including blocks)
• [x] Add parser tests.

[dishmint]

I should probably add delimiter parser tests for each condition, but doesn't seem super pressing atm.