Update Macaw version and add a cask

I'm new to pull requests so bear with me.
I saw that the Macaw cask was broken due to checksum errors, so I decided to fix that, only to discover a new version was out, so I updated that too.
Then I decided to fling in some of my own casks. One for Popcorn Time, the others for two audio plugins, but I cancelled the plugins and only added the one for Popcorn Time.
I hope all is good and proper with the pull request...