Improve heading syntax region

[amarakon]

Markdown headings have at least one whitespace character after the hashtag(s).

This is a heading

#This is not a heading

[alerque]

This is an interesting one and I'm not 100% sure what to do. This rule is implemented differently across different Markdown parsers. The original daring fireball "spec" wasn't clear, and bath ways started getting implemented early on. These days many of the more formalized specs such as CommonMark, Pandoc FM, GitHub FM, etc. have converged on requiring the space. Many older or less spec dependent parsers don't care. Others like it-markdown have extensions to make them optional.

This raises the issue (yet again) of what this plugin targets. This is very much a legacy project and I think it should probably default to targeting as generic and legacy a "flavor" as possible. There are other plugins for Pandoc specific syntax or CM or whatever.

However given the daring fireball examples use a space (even if it wasn't required) I wonder how many people's usage this would actually break and whether the extra reliability and fewer false positives might be worth it anyway.

Thoughts?

[tomtomjhj]

See also: #598

[amarakon]

This is an interesting one and I'm not 100% sure what to do. This rule is implemented differently across different Markdown parsers. The original daring fireball "spec" wasn't clear, and bath ways started getting implemented early on. These days many of the more formalized specs such as CommonMark, Pandoc FM, GitHub FM, etc. have converged on requiring the space. Many older or less spec dependent parsers don't care. Others like it-markdown have extensions to make them optional.

This raises the issue (yet again) of what this plugin targets. This is very much a legacy project and I think it should probably default to targeting as generic and legacy a "flavor" as possible. There are other plugins for Pandoc specific syntax or CM or whatever.

However given the daring fireball examples use a space (even if it wasn't required) I wonder how many people's usage this would actually break and whether the extra reliability and fewer false positives might be worth it anyway.

Thoughts?

I think we should add the space by default, then add an option to remove the space. Also, in Pandoc Markdown, #. can be used for ordered lists. This creates a false positive.