Rhythmbox

* Remade the UI (With the help of https://www.curseforge.com/members/nanostel06)
* Music controls can now be changed by typing the value
* Music should not overlap anymore when going out of render and back
* **Custom music mods that use CustomRhythmboxMusic as their root folder will get disabled in a future update. Please create a new empty project in the devkit and MOVE all files from your project to the created  project. You can then link this new project to the same mod website by clicking the "Is existing mod" button and typing your project id from the old mod.**