IDEA: scroll parser which uses javascript template literals

This is somewhat related to the `particleExplorer` discussion in #154, except instead here [javascript template literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals) are used

```
displayBelowParticle
templateLiteral

• ${this.get("field1")}


• ${this.get("field2")}

templateLiteral scroll
ul
li ${this.get("field1")}
li ${this.get("field2")}
someParticle
field1 value1
field2 value2
```

The subparticles of `templateLiteral` (without an atom following the cue) will be expanded as a normal javascript template literal. If the first atom is `scroll`, then it will be called using the tagged functon scroll (i.e. ``scroll`` ``). The scroll tagged function will convert to html, I guess.

In either case, some variable (like `this`) above will be set to allow access to the selected particle.

Start by reading the related particleExplorer discussion in #154 and compare the proposed template-literal forms with the existing parser behavior. Identify the parser entry point and tests that would need to cover both ordinary and tagged template literals, then define the expected expansion and the value available through `this` before implementation.

Written by the indexing model from the issue text.