Setting for error display mode

[xavdid]

Hey there!

I was wondering if there was a setting for how linting errors are displayed inline (or if there isn't, if we could add one).

a ts error:

This is fairly quiet (you have to be looking at that line to see the little red squiggle). Contrast this with standard's sublime-linter:

The dot + box is much more visible.

I'm not sure the scope of the work (if it's as simple as adding a setting to change how invalid lines are marked vs a large code change), but I think it'd be worth looking into!

[zhengbli]

PRs are welcomed. These lines can be a good start:

https://github.com/Microsoft/TypeScript-Sublime-Plugin/blob/2da61f59d231b5442e1a7136aedcb9705ad099e2/typescript/listeners/idle.py#L164