Allow ESC key to dismiss modal popups

[brian-learningpool]

Thinking of things like the tutor, hotgraphic items, etc., it would be useful if the ESC key could dismiss these and return to the course. It's quite a common behaviour now, e.g. Gitter, Slack, etc.

[moloko]

I seem to recall this couldn't be done on account of ESC being a special key for screen readers... I thought perhaps I saw a PR for enabling it when accessibility wasn't active though, might be wrong

[moloko]

ah, it was for closing the drawer see #612

[oliverfoster]

this line for drawer https://github.com/adaptlearning/adapt_framework/blame/master/src/core/js/views/drawerView.js#L39 needs to be _isActive rather than _isEnabled, like e9b7f9d

[moloko]

I think that's everything now?

[moloko]

added to hotgraphic in v2.0.7