[Discussion]: Allow headings anywhere that block-level items can exist

[vhyrro]

This is less of a proposal and more of a call for discussion.

In the current 1.0 syntax, headings are special in that they are called "structural". This means they cannot be placed in areas like:

• The content of lists
• The content of long-form definitions

Somewhat counterintuitively, I believe it may be beneficial to allow headings everywhere and not stress it as much as we currently do. This provides the following benefits:

• Parsing is much simpler, as a single "block" node can be defined which can contain all block-level syntax.
• Headings become much easier to embed within standard ranged tags (e.g. |example)

Recall #35, where I propose that Norg syntax should not be bothered with typesetting. I believe this should also translate over conceptually to headings by freeing them from the artificial limitation of existing only in the top level of the document.

[boltlessengineer]

instant thoughts:

• heading in the top level of the document will "structure" the document (by consuming all blocks below it)
• headings can be nested as before
• headings not at top level of the document won't consume the blocks below it.

If I can rename the word section to heading as I suggested before, I think new syntax seems more clear.

• a "section" consists of a heading and all blocks (except headings because they will start another section) below it
• a section can only exist in top level of the document
• a "heading" is made up of * prefix followed by single-line paragraph (called "title", If only we can say it is just a paragraph...)
• a heading can have a level but doesn't have any meaning by itself
• the level of a section is determined by the level of its associated heading.

* a heading         <- start point of section-1 (level 1)

blocks...

**** a sub heading  <- start point of section-1.1 (level 2)

blocks...
                    <- end point of section-1.1, section-1
* another heading   <- start point of section-2 (level 1)

> * heading <- we can put a heading inside quote, but this won't make a "section"

paragraph   <- so this doesn't belong to the quote