Add Logisim

[turtlebasket]

Description

Adding support for Logisim (Evolution) files. Logisim is a popular FOSS tool for digital system design, typically used for educational purposes. Logisim files are actually just XML but contain circuit logic that can be viewed and simulated in Logisim, making the .circ format somewhat comparable to .ipynb.

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?q=path%3A*.circ+lang%3Axml&type=code
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • [URL to each sample source, if applicable]
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

• 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:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.circ+language%3Axml
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/sam-astro/Astro8-Computer/blob/main/cpu-circuit.circ
      • https://github.com/rosco-m68k/rosco_m68k/blob/develop/design/r0/logisim/address_decode_v2.circ
    • Sample license(s): MIT
  • I have included a syntax highlighting grammar: [URL to grammar repo]
  • I have added a color
    • Hex value: #008016
    • Rationale: Just picked the shade of green from the Logisim logo
  • I have updated the heuristics to distinguish my language from others using the same extension.

• I am fixing a misclassified language

  • I have included a new sample for the misclassified language:
    • Sample source(s):
      • [URL to each sample source, if applicable]
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

• I am changing the source of a syntax highlighting grammar

  • Old: [URL to grammar repo]
  • New: [URL to grammar repo]

• I am updating a grammar submodule

• I am adding new or changing current functionality

  • I have added or updated the tests for the new or changed functionality.

• I am changing the color associated with a language

  • I have obtained agreement from the wider language community on this color change.
    • [URL to public discussion]
    • [Optional: URL to official branding guidelines for the language]

[lildude]

As this is standard XML, the extension should be added to the XML language entry. We try to limit the splitting of things like XML and JSON to new entries only when they deviate and have their own grammar.

The samples/Logisim/astro8_cpu.circ sample is also way too big. Please remove it or replace it with a smaller sample.

[turtlebasket]

Sounds like it'd be appropriate to convert this PR to add the .circ extension to XML and move the samples (except for the large one) to samples/XML instead?

[turtlebasket]

Alrighty, updated- lmk if anything looks off with this

[Alhadis]

@turtlebasket Are there many .circ files that lack an XML header? If not, then these files should be classified correctly as XML on GitHub, as Linguist has a dedicated strategy for recognising files that begin with the line

<?xml version=

If many .circ files in-the-wild lack these headers and aren't receiving any highlighting, then this addition is still valid (and you can dismiss this feedback).