[HuiJun]

The textual notations of the OMG SysML v2 (.sysml) and KerML (.kerml) specifications, highlighted by the Apache-2.0 TextMate grammars in Open-MBEE/sysml-v2-textmate.

Description

Adds the two textual notations of the OMG Systems Modeling Language v2 family: SysML (.sysml, SysML v2) and KerML (.kerml, Kernel Modeling Language), the kernel language SysML v2 is defined on. Both are highlighted by the TextMate grammars in Open-MBEE/sysml-v2-textmate (Apache-2.0; scopes source.sysml and source.kerml), which are generated from the keyword tables of the OpenSysML parser and shipped by its VS Code extension. The grammar repository was added with script/add-grammar; both scopes compile cleanly with the grammar compiler.

Neither extension is claimed by an existing language, so no heuristic is needed. .sysml is well past the usage threshold; .kerml sits at about 2,000 files and is included because it is the same language family, grammar repository and maintainers, and a .sysml model routinely sits beside the .kerml library it imports. If you would rather see more usage first, KerML can be dropped from this PR and proposed later.

SysML carries the aliases sysmlv2 and sysml2, the names in common use for fenced code blocks.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • .sysml: https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.sysml (about 24.5k files)
      • .kerml: https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.kerml (about 2k files)
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/relay-probe-demo/mission.sysml
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/verdicts-demo/rover.sysml
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/runtime-showcase/spacecraft-comms.sysml
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/parser_features_demo_declarations.kerml
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/parser_features_demo_binding.kerml
      • https://github.com/Open-MBEE/OpenSysML/blob/6e86049b3be65f0cbbbb17f3850903b0f76291e4/examples/parser_features_demo_advanced_bodies.kerml
    • Sample license(s): Apache-2.0 (all six, from Open-MBEE/OpenSysML)
  • I have included a syntax highlighting grammar: https://github.com/Open-MBEE/sysml-v2-textmate
  • I have added a color
    • Hex value: #3F51B5 (SysML), #5C6BC0 (KerML)
    • Rationale: indigo chosen deliberately for SysML (no existing language uses it); KerML is a lighter shade of the same hue so the two languages of the family read as related on a repository's language bar.
  • I have updated the heuristics to distinguish my language from others using the same extension. (Not needed: neither .sysml nor .kerml is used by any other language.)