Fix token aliases and upgrade Prism

[kitten]

Fix #29
Fix #14

This adds support for token aliases, which was unfortunately missing before. It also upgrades prismjs and ensures that js-extras is included.

@karlhorky Sorry, this might be as good as we can get it for now without some tremendous extra-effort. Testing these changes would be appreciated, if you have the time 🙌

[karlhorky]

Approach sounds pretty good to me! What does the support for token aliases enable?

[kitten]

@karlhorky it's basically sth that is already present in Prism themes but that I forgot to add support for. In certain cases themes can specify "aliases" which are more specific types of tokens that should take precedence over the other types. One example afaik are keywords being marked as "important" in JS

[karlhorky]

Ah cool, yeah then I suppose that may enable things like what I was trying to accomplish with styling the = and ", cool!

#29 (comment)

[karlhorky]

Oh I've guess it won't for this exact case (see my request to improve the Prism.js tokenization: PrismJS/prism#1871) but it will maybe improve other cases.

[kitten]

Yeah, I don't see any regressions from this PR, so I'll ship it, and if Prism improves some syntaxes we'll definitely profit from it 😅

[karlhorky]

Awesome, thanks! Is there going to be a new version published too?