Refactoring

[pietervdvn]

• [x] Move ...2MD's into own package (docgen or something)
• [x] Make union find and order find generic for graphs, move into Graphs (out of precedence)
• [x] Parser: decouple typedefs from comments etc
  • [x] Check docstrings withing adt-sums. Where do they go?
  • [x] Docstrings within categories
  • [x] Check comments withing expressions. Where do they go? (Just nowhere, but thats no problem)

[pietervdvn]

Docstrings are handled within ADT-prod

[pietervdvn]

2MDs superseded by #77