Another Interstellar update: new icon, microblogging support, editing/deleting capabilities, youtube embedding, and more

To start, Interstellar finally has an app icon; thanks to @BenjMathis1 for designing it and @dannii_montanii for helping implement it into the app! (https://raw.githubusercontent.com/jwr1/interstellar/e55763688df9f62b12997515830344b701e1f47c/assets/icons/logo.png)...