beginScope and endScope

[joshgoebel]

Resolves #3156.

Changes

Adds endScope and beginScope:

  {
    begin: /"/,
    end: /"/
    beginScope: "string.delim",
    endScope: "string.delim",
    scope: "string"
  }

To produce something like:

<string>
  <string.delim>"</>
    hello world
  <string.delim>"</>
</>

Multi-match may also be used with end, just as with begin.

Checklist

• Added tests, or they don't apply here because...
• Updated the changelog at CHANGES.md

[joshgoebel]

Two commits are probably easier to review separately.

[NullVoxPopuli]

I love this! in certain templating languages dealing with nested stuff is tricky, and this is perfect!