[Redesign] Change Play and Shuffle button design

[snppls]

The Play and Shuffle buttons are too prominent and distracting in it's current state IMO.

I would propose something like the mockup presented here. It involves reducing the size of the buttons slightly and removing the color - it also incorporates a drop down arrow in place of the 3 dot hamburger menu thing (which currently feels disconnected from the current Play and Shuffle buttons). I believe it also keeps the design logic of other parts of the app where icons are represented by black or white outlines only.

[Chaphasilor]

The current design is only temporary, for making it possible to use the new queue features before the new design is finished. Take a look at #220 (comment) and #220 (comment) for a mockup of how it should look in the end. The actual elements might still change, depending on the features that are available and planned.