Update syntax-variables.less to include language entity colors

[savetheclocktower]

Suppose you've written a package that makes some sort of editor enhancement. For various reasons, you'd really like to know what color is used to highlight variables in their syntax theme.

The good news is that Pulsar defines a list of variables in syntax-variables.less in each of the eight built-in themes which lists this token and others. (Amazingly, not all of them actually consume these variables in the rest of the stylesheets, so it may only be coincidental when the values line up; but B+ for effort.) Pulsar also defines some fallback values so that these values can at least be used consistently in a user's stylesheet file, and in any package stylesheet, without Less complaining about an undefined variable.

Somehow, though, these variables never made it to the template that PPM uses to generate new syntax themes. I've fixed that here. I've also taken the liberty of adding two variables — @syntax-color-comment and @syntax-color-string — that I can't believe were excluded from this list initially.

Will this make much of a difference when most community themes aren't actively maintained? Maybe not. But the best time to plant a tree was back in 2015 (when some other trees were planted in a different repository) and the second best time is now.

[DeeDeeG]

I trust the explanation in the PR body, and based on that, looks good to me!

Do we need to add @syntax-color-comment and @syntax-color-string in static/variables/syntax-variables.less file of Pulsar core repo as well? Would it break users' existing themes?

[savetheclocktower]

We do need to add them, yes. I'll tackle them whenever.

There's no chance of breaking users' themes. The only things that would break are things (packages, etc.) that assume the presence of these variables without checking — and since lots of themes already don't have those variables (because they weren't in the generated template!), I can't imagine there are many of those.