Add support for the BASIC family of programming languages

[telnet23]

Description

As I reported in #5156, many BASIC programs have been incorrectly labeled as VBA (or Visual Basic .NET if they have not been updated since #4725). There are numerous dialects of BASIC (e.g. AppleSoft, Commodore, GW-BASIC), but most dialects share similar syntax and reserved words, and all dialects are collectively known as BASIC. At the very least, a file with the extension .bas and line numbering should be labeled as BASIC rather than Visual Basic .NET or VBA. Therefore, I have added a BASIC language along with an appropriate grammar and sample, and I have added a heuristic to check for line numbering.

Checklist

• I am adding a new language
  • The extension of the new language is used in hundreds of repositories on github.com
    • https://github.com/search?q=10+20+30+GOTO+extension%3Abas&type=Code
  • I have included a real-world usage sample for all extensions added in this PR
    • https://github.com/telnet23/bas/blob/master/mandelbrot.bas
  • I have included a syntax highlighting grammar
    • https://github.com/telnet23/language-basic
  • I have updated the heuristics to distinguish my language from others using the same extension
    • Added a heuristic to check for line numbering

[zspitz]

Your query searches for GOTO, but AFAICT the search is case-insensitive. GoTo is a keyword (albeit an infrequently used one) in VBA and VB.NET.

Do members of the BASIC family generally use all-caps GOTO? Would it be worth adding GOTO to the heuristic for BASIC languages and GoTo for VBA and VB.NET, as a last-case heuristic?

[telnet23]

@zspitz Correct, the GitHub search is case-insensitive, which is why I also included 10 20 30 in the search. Line numbers in BASIC programs are often (but certainly not always) chosen to be multiples of 10. The search is not all-inclusive but it does provide clear evidence that BASIC programs have been incorrectly labeled as Visual Basic .NET or VBA.

Some dialects of BASIC are case-insensitive while others are case-sensitive, requiring uppercase keywords. Even in dialects of BASIC that are case-insensitive, programs are sometimes written entirely in uppercase anyway.

[telnet23]

@lildude Any update on this pull request?

[lildude]

@lildude Any update on this pull request?

I was waiting for you to address the failing tests as the PR isn't complete whilst they're failing.

[telnet23]

@lildude OK, all checks have passed now.

[lildude]

LGTM 🙇