Adds a download button in audio frames

Adds direct .mp3 links to tracks which allow for preview downloads, so you don't need to log-in an stuff.

Adds a button to the doc editor toolbar which toggles lights ON (black text on a white background) and OFF (white text on a black background). Mixing this with the fullscreen mode results in a more comfortable writing experience for your eyes.

Restores the font and color usage of the discord app to its former glory.