Recognize additional Dyalog APL file extensions

[ararslan]

Description

Dyalog APL uses a variety of file extensions in addition to .apl and .dyalog. The others are for specific kinds of definitions:

• .aplf for functions
• .apln for namespaces
• .aplc for classes
• .aplo for operators
• .apli for interfaces

At present, none of those extensions are recognized as APL by linguist; this PR adds them.

Checklist:

• I am adding a new extension to a language.

  • The new extension is used in hundreds of repositories on GitHub.com

    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.aplf (11.2k)
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.apln (244)
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.aplc (240)
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.aplo (330)
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.apli (2, lol)
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.apls (54)

  • I have included a real-world usage sample for all extensions added in this PR:

    • Sample source(s):
      • .aplf: https://github.com/Co-dfns/Co-dfns/blob/f5ad1382e13dee0d56b7864a35e8fd740c2fec3a/ws/DISPLAY.aplf
      • .apln: https://github.com/nunezco2/quAPL/blob/23ccdfde79fcea30f51f8280f0197aca3377dc15/APLSource/circuit.apln
      • .aplc: https://github.com/aplteam/Tatin/blob/527049530026fe03c94b5a99cc2eb82029d2adcf/APLSource/Tester2.aplc
      • .aplo: https://github.com/rodrigogiraoserrao/ANNAPL/blob/4fbf53f7764e2b46ade62e398906af1c8ea1bf72/_Train.aplo
      • .apli: https://github.com/aplteam/ADOC/blob/3c23c88ef6a9d36aa5e7322ff26b5adeda1e20f4/APLSource/TestCases/testinterface.apli
      • .apls: https://github.com/Brian-ED/raylib-apl/blob/2a040bde6ba8a60bbee0e149c7f5904c8140268b/examples/3d-duck.apls
    • Sample license(s):

  • I have included a change to the heuristics to distinguish my language from others using the same extension.

    • Not applicable as these are only used by APL

[lildude]

This PR will be held back until all of the extensions you are adding each meet our usage requirements.

Rather than keeping this hanging around potentially forever, I recommend adding only those that meet our requirements. Users can always use an override for the others until usage is sufficient to be added.

[lildude]

In addition to my other comment, real world samples are needed for all extensions being added. See CONTRIBUTING.md.

It's also worth ensuring that the current grammar will actually highlight these files correctly too.