Add a theme to vscode-nim?

[AMSwift73]

This follows up on my earlier issue report and on the Nim forum thread https://forum.nim-lang.org/t/12697.

Proposal: Add nim-ready themes to the vscode-nim extension. The theme offered is still in beta and needs review, but it does:

1. Recognize Nim code tokens
2. Helpfully colorize indentation levels, so important in Nim, and
3. Ensure that only Nim brackets are colorized by the "colorize bracket level" option.

I apologize for the messy commit history; I'm new to git, github, and the github desktop app.
readme.md should be unchanged, package.json should only have a block added pointing to a theme (near end of file), and the only significant addition is one theme in a new "themes" folder.

[jmgomez]

Why this needs to be part of the extension though?

[AMSwift73]

There is no strict need for one or more themes to be part of the standard Nim extension.

However, one part of this extension that really IS needed - and already present - is the correct recognition of Nim tokens, including indentation and brackets. Adding themes that more fully translate this vital job into visuals for developers helps complete this core task.

Therefore, this PR intended to be a) small, b) relatively unimportant in itself, and c) usefully support a much more important job.

[Araq]

Does this do the tokenization properly? A good test case is system.nim after line 145:

  proc new*[T](a: var ref T, finalizer: proc (x: ref T) {.nimcall.}) {.
    magic: "NewFinalize", noSideEffect, deprecated: "pass a finalizer of the 'proc (x: T) {.nimcall.}' type".}

Messes up my current tooling because of the pragma syntax used inside a string literal inside a pragma.

[AMSwift73]

Araq,
Quick Q: Do you expect the whole string "pass a finalizer...", including "{.nimcall.}", to be of a uniform color - as displayed here on github - or that the entire pragma {.magic: ... type.} be a uniform color, or am I misunderstanding?

If the former, then vscode with vscode-nim should already accommodate you? If the latter, that's (at least) a syntax file issue; changing only the theme will not help.

[Araq]

Quick Q: Do you expect the whole string "pass a finalizer...", including "{.nimcall.}", to be of a uniform color

Yes, this one. There is not much complexity going on here, just tokenize as always inside {. .} -- like they would be ( ).

[jmgomez]

@AMSwift73 can you provide some screenshots showing how this actually helps? Bonus points if you also make the PR so it doesnt modify existing lines but only your actual changes

[jmgomez]

Does this do the tokenization properly? A good test case is system.nim after line 145:

  proc new*[T](a: var ref T, finalizer: proc (x: ref T) {.nimcall.}) {.
    magic: "NewFinalize", noSideEffect, deprecated: "pass a finalizer of the 'proc (x: T) {.nimcall.}' type".}

Messes up my current tooling because of the pragma syntax used inside a string literal inside a pragma.

@Araq doesnt yours look like this?