Remove -fobject-code from .ghci

(this slows down reloads on modifications)
Get rid of StandaloneDeriving
Derive more instances
Remove unused language extensions
Minor refactoring
parser: Try to parse definition lists right before text paragraphs
Add support for markdown links (closes #336)
Allow markdown links at the beginning of a paragraph
Update documentation
Add support for markdown images
Allow an optional colon after the closing bracket of definition lists

This is to disambiguate them from markdown links and will be require
with a future release.
whitespace only
Fix re-exports of built-in type families

Fixes #310