Entering Mature channels requires re-confirmation every time

[KaoNocturatzu]

When you enter a mature (18+) channel, you have to re-confirm you're over 18 every time you click on the channel, even if you've already typed in that channel. It should confirm once and remember your affirmation for all channels on a per server basis.

[Rexogamer]

This is a duplicate of #272 - this is also intended behaviour, but we're considering some sort of alternative.