New package: Code syntax highlighter for SILE

[Omikhleia]

New 3rd-party package: highlighter.sile
Available on Luarocks as part of the SILE ecosystem.

[Omikhleia]

A logical follow-up is to propose a SIL lexer to Scintillua, so there you go for a proposed PR: orbitalquark/scintillua#144

[Omikhleia]

highlighter.sile release 0.2.0, with a few new goodies, including the SIL "TeX-like" syntax highlighter (which couldn't be up streamed to Scintillua due to not being context-free, but I thank them for their valuable feedback on the way).

[no-vici]

Wow, this is a really cool highlighter!

Thank you so much for injecting into SILE.