section selector with level specifier?

[yshavit]

Right now, section selectors don't differentiate between the level of header:

# foo

☝️ this...

## foo

☝️ ... matches the same as this.

Do we want to add an option to specify the level?

[yshavit]

Assuming yes, what would the syntax be?

Suggestion:

{1}# foo

This would match an h1 heading: # foo but not ## foo.

Alternatively, we could do:

#{1} foo

This is clearer, but I'd need to think how it would interact with the possible quoting options being discussed in #56 (e.g. {"EOF"}text text textEOF).

Regardless, we could also add >, <, >=, <= in front of the number:

{>=2}# foo

... would match ## foo and ### foo but not # foo.