Add syntax highlighting for meson build system

[asakovets]

It is basically a port of upstream syntax highlighting for vim, but a bit less noisy (e.g numbers are not colored).

[niten94]

but a bit less noisy (e.g numbers are not colored)

I think it's fine to highlight numbers and symbols, since users chould choose a colorscheme like simple where highlighting on some elements is minimal or none.

I'm inexperienced with syntax files but based on examples and the link in the file, maybe this could be added:

    - constant.number: "\\b(0|[1-9][0-9]*|0b[01]+|0o[0-7]+|0x[0-9a-fA-F]+)\\b"
    - symbol: ','
    - symbol.operator: "[-+*/%?.:=!+<>]"
    - symbol.brackets: "[(){}]|\\[|\\]"

@Andriamanitra
Sorry to ping, but may I request you to review this? I've seen some open source desktop software using Meson, so I think this would be nice to add. Actual examples I know other than documentation include util-linux, seatd, Xorg server and wlroots.

[Andriamanitra]

I'm not familiar with meson but I tried it with a couple meson files and it seems to work alright.

[asakovets]

Hi, sorry for the delayed reply. I almost forgot about this PR. I will look into it when I have time.

[niten94]

I don't think you should be the one apologizing, considering that this PR received no attention for a long period of time. I've actually used your syntax file sometimes to view Meson build files, but wasn't sure when to properly review it myself.

However it would still be appreciated if it's fine with you to address the comments, so that this can now be merged and included by default.

[asakovets]

Hi, @niten94 , @Andriamanitra could you please have another look?

[niten94]

@dmaluka @JoeKar
Not sure who to ping but this has now been reviewed, so may this be merged?

[JoeKar]

The problem with reviews resp. approvals of non-maintainers is, that they aren't included in the filtered search:
https://github.com/zyedidia/micro/pulls?q=is%3Apr+is%3Aopen+review%3Aapproved

This will most probably hit a lot more PRs where the community gave their approval.

Anyway, I will have a short look.