Add BBCode language

[Nixinova]

• This resolves [Language Addition] BBCode #7134

Description

Adds BBcode, a language used usually on forums but does get some usage on github too.

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:
      • *.bbcode: 1.1K+ files
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample: source, under MIT
  • I have included a syntax highlighting grammar: url
  • I have added a color
    • Hex value: #caff42
    • Rationale: BBcode website
  • I have updated the heuristics to distinguish my language from others using the same extension.
  • Note: the submodules bork up my local git, i hope the files committed properly