Fixes a number of issues:
- Headings underliners now have the correct length
- Newline+Tabs in descriptions are replaced by two newlines to make a proper paragraph
- [br] are replaced by two newlines, making a proper paragraph
- Properly parse internal hyperlinks in constants description
- Fix broken internal links due to missing newlines
- Show method header even when it has no description, to have something to reference in hyperlinks