Add asciidoc support

[haslingerm]

• Added grammar definition for asciidoc based on work by Matt Neuburg
  • Author expressed permission to use his work under MIT license with attribution in a GitHub issue despite not providing a license file
• Solution compiles, tests are green
• Ran TextMateSharp.Demo against a sample .adoc file
  • No exceptions, looks good
  • Some defects for complex documents, but overall ok (grammar is pretty complex, would require considerable work to get a better result)
• Configuration files (cgmanifest.json, package.json, package.nls.json) added on a best-effort basis

If I missed a configuration, can fix an error or improve the PR somehow please let me know.

[danipen]

Test failed. I think the fix is trivial.

[haslingerm]

Yeah, missed the second tests project, sorry, on it