[RFC] Support embedded JSON and YAML string literals

[tshort]

We already have support for cxx""" ... """. This adds support for similar embedded styling for JSON and YAML, ala:

a = yaml"""
one: 123
two:
  twoA: hello
  twoB: world
"""

If we add something similar to https://github.com/JuliaLang/Julia.tmbundle, we can cover Atom, TextMate, Sublime, and GitHub markup (so the block above will have enhanced highlighting).

Note, JSON and YAML string literals aren't in JSON.jl (JuliaIO/JSON.jl#113) and YAML.jl, yet. So, we should probably wait to get some consensus here.

This feature helps for including structured data in the same file as the Julia source code.

[sglyon]

Thanks for adding this. Let's see what happens inside JSON.jl and YAML.jl

I think it'd be confusing to have highlighting for a feature that isn't supported by any packages.