Add a setting to disable the wavy underline which the extension adds for all types

[c10b10]

When enabling the extension, a blue wavy underline appears under all types. I presume its point show the developer that they can hover this type, but it it's unnecessary and adds to the clutter.

[sturgeonphillip]

I'll second this one. Can the blue squiggly line be made optional?

Something that hasn't been marked as learned appears on the Problems panel (although one could argue it's a problem if you haven't learned it yet haha).