Feature request: Provide outline symbols

[wjandrea]

Example wikitext:

=H1=

foo

==H2==

bar

Right now the outline says "No symbols found in document 'tmp.wiki'".

I would want it to show:

• =H1=
  • ==H2==

like what it shows for Markdown:

• # H1
  • ## H1

# H1

foo

## H2

bar

[bhsd-harry]

This feature is already provided by WikiParser.