Add setting to display headings in graph view

[juen]

New feature request (more concise and easier example) here:

Display headings and blocks in graph view

Add a setting to toggle the display of headings as nodes around the parent note. This would be great to visually explore notes of meetings, articles or book summaries. In connection with the already existing Attachments toggle it would yield a great tree-like graph if the parent note would first have nodes for all headings and then nodes for all attachments that belong to each heading. Clicking on the heading note would link directly to the heading in the parent note i.e. [[Parent note#Headin…