Add Ohm Language

[novusnota]

Adding an Ohm language for .ohm extension. Expected to only occur once per repo.

Description

Ohm is a parsing toolkit consisting of a library and a domain-specific language. One can use it to parse custom file formats or quickly build parsers, interpreters, and compilers for programming languages.

The Ohm language is based on parsing expression grammars (PEGs), which are a formal way of describing syntax, similar to regular expressions and context-free grammars. The Ohm library provides a JavaScript interface for creating parsers, interpreters, and more from the grammars you write.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com. As this language is used for making parsers, and interpreter/compiler frontends, it's extension is expected to occur only once per repository (except for the repositories in ohmjs organization):
    • Search results for each extension:
      • Not forks (~440 files)
      • Not forks, excluding ohmjs organization (~380 files)
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • ohm-grammar.ohm is adapted from it's version in ohmjs/ohm
    • Sample license(s): MIT License
  • I have included a syntax highlighting grammar: novusnota/vscode-ohm
  • I have added a color
    • Hex value: #A469F8
    • Rationale: Most used on the language website, primary color.
  • I have updated the heuristics to distinguish my language from others using the same extension. No other language has the same extension, so I didn't update heuristics.

[novusnota]

For what it's worth, here's a complete and well-tested tree-sitter grammar for Ohm, which may be used by the relevant GitHub team to supersede TextMate grammar from this PR once or if it gets merged :)

[novusnota]

Converted to draft to enhance and/or re-write the grammar :)