Adds the Dracula color scheme as a theme. There's also a bonus gray theme because I always felt the default dark scheme was far too dark with the pure black background, but if I changed it to my liking I'd probably make more people upset than happy.
Teeeeechnically this also changes the stock themes in an incredibly minute way that I bet nobody will notice if it wasn't written here: checkboxes (when checked) now have the same color as buttons instead of the default Bootstrap color.
Copied from previous PR: