Let macOS handle adaptive appearance by using semitransparent icons

The other approach was cool, but this is a lot simpler and is how Apple does it with their own menu items

Fix handling and names of scripting options

Update copyright year in Info.plist

Actually fix Custom Caffeination window activation

Add Sparkle, CaffeineKit to, and remove Down from, licenses

Update version to 1.3.1

Correct typos in Spanish translation

Run caffeinate process checks when Caffeination finishes

Bump version number to 1.2.1