Determine if there is a good way to "validate" Markdown

[jacebrowning]

During Item validation, see if we can check for common formatting mistakes:

# mismatched formatting
**word*

# missing list separator
invalid list:
  - item1
  - item2

[ngbrown]

There is a markdownlint implemented in Ruby. A Node.js version builds on those rules.

A Python version was started, but didn't get very far.

If the files being edited were .md files, then the editors have plugins that will highlight errors while typing. (ex. Visual Studio Code, Sublime, or Atom).

While Sublime plugins are Python based, the Sublime markdown linter actually shells to the Node.js version, which has to be installed separately. That would be an option for checking at the command line, especially imported text.

[neerdoc]

Standard Markdown (without plugins) is quite limited. It should be relatively straight forward to write few lines of regexp to validate it.