Give Karthus's Q an indicator

Now that Quickcast with Indicator has been the default for quite some time, it should be the case for Karthus's Q as well.

Lacking an indicator makes sense for Yasuo's Q since it functions exactly like a stab. But Karthus's Q has no reason to lack the indicator. I understand that the point is to make it slightly easier to spam at high CDR, but it really doesn't do that. If you're spamming it, you're letting go of the key anyway.

It only screws up the player's perception of his maximum range.