Remove spell check from selected text/highlighted code

[geofferb]

Describe the solution you'd like
For spellcheck to be removed from a selection of text, rather than the whole page. This feature can also be added to the code highlighter, since 99% of the time spellcheck is not needed when writing code.

Describe alternatives you've considered
The language can be manually changed to something else, but this takes many clicks.
NoteHighlight2016 implements this by changing highlighted code to Latin (World) which does not have spell check.