julia-mode.el: Highlight string interpolation

[Wilfred]

ruby-mode does this, it would be nice to do it in julia-mode too. E.g. println("hello $user") should highlight $user differently.

[PythonNut]

Will this extend to arbitrary expressions, or just simple substitutions?

[JeffBezanson]

This seems to require parsing arbitrary expressions. I would say not worth it just for this.

[Wilfred]

Some useful notes in this ticket: #164

I'm game to try this unless there are any objections. However, we have bigger string highlighting problems at the moment (triple-quoted strings don't work).

A related easy win would be to highlight regexp metacharacters, something like this:

This doesn't require any parsing sophistication. Julia's syntax is nice here because r".*" is a proper Regex type, whereas in Python it's just a string with different lexing rules.

[yuyichao]

Moved to JuliaEditorSupport/julia-emacs#3