Consider separating directive delimiters' color from control block delimiters'

[bricelam]

I tend to only use directives at the top of a file, so the bright yellow cue that I'm switching contexts really isn't needed. It would be nice to at least have the option to configure this separately.

On the other hand, the include directive is likely to appear anywhere in the file, so configuring it this way might be a pit of failure.