Update Dockerfile lexer

Approved-by: m m <marnitto@gmail.com>

Add support for the Fennel programming language

Add HLSL lexer

Approved-by: Anteru <bitbucket@ca.sh13.net>

This is a pretty straightforward language in the lisp family with a
small number of special forms. Since Fennel runs on the Lua runtime,
the list of builtins is the same as that of Lua, so it might be
possible to re-use the definition from the Lua lexer, but since I
don't know Python I couldn't figure out how that would work; maybe
someone else could add that.

Add Dockerfiles new keyword in the lexer
Improve lexer to parse json arrays on specific commands
Handle line breaks as a bash syntax

- Also added a snippet to the example file where a string shows up (uncommon in HLSL).

This introduces support for some missing features to the Handlebars lexer:
Partials and path segments. Partials mostly appeared to work before, but the
`>` in `{{> ... }}` would appear as a syntax error, as could other
components of the partial. This change introduces support for:

* Standard partials: `{{> partialName}}`
* Partials with parameters: `{{> partialName varname="value"}}`
* Ddynamic partials: `{{> (partialFunc)}}`
* Ddynamic partials with lookups: `{{> (lookup ../path "partialName")}}`
* Partial blocks: `{{> @partial-block}}`
* Inline partials: `{{#*inline}}..{{/inline}}`

It also introduces support for path segments, which can reference content in
the current context or in a parent context. For instance, `this.name`,
`this/name`, `./name`, `../name`, `this/name`, etc. These are all now tracked
as variables.