renamed webp-quicklook to webpquicklook

[vitorgalvao]

As stated by @rolandwalker in #3344, we should:

try to avoid the case where a Cask name differs only by the placement of a hyphen.

However, it seems we forgot to change these (the other being emin-webpquicklook.rb), even though they were part of the rule’s mention. This PR addresses that.

[rolandwalker]

What I was speaking to in that particular case was that webp-quicklook.rb and webpquicklook.rb differed only by a hyphen which seems counter to usability. We resolved it by prepending emin-.

But I have no problem with this change if it makes sense to you. Really only app Casks and font Casks have defined tokens. Everything else is still unconquered and irregular. Though we should get to them at some point, for the sake of "upgrade".