Improve playback control button affordance

[jacobpgn]

For #12

This adds:

• button alpha change on hover state
• more recognisable next/previous icons
• smaller target areas to make it harder to hit the wrong button

[jacobpgn]

My first time using Xcode and Swift, so I apologise in advance if I've done anything weird here!

[kmikiy]

Thanks for the PR 👌🏻I'll check it as soon as i can

[kmikiy]

I've updated the size of the next and previous buttons and added a more subtle pressed in state (.leftMouseDown). What do you think?

so I apologise in advance if I've done anything weird here!

No worries. Nothing weird. By the way this whole project could use some refactoring 😬

[jacobpgn]

Pressed in state looks much better now, nice one!

I think the previous button is positioned a few points too high, are you seeing that too?

[kmikiy]

I think the previous button is positioned a few points too high, are you seeing that too?

Could be. The auto guidelines in xcode kept snapping the buttons in position.

I also noticed that the pause icon is a bit fuzzy on the top left and bottom right. I haven’t looked in to why that’s happening. Maybe due to the resolution?