Delete arrow_expand_art.png
Add new icons for expand and contract in mini player
Use contract image in mini player
Merge branch 'pr/112'

* pr/112:
  Use contract image in mini player
  Add new icons for expand and contract in mini player
  Delete arrow_expand_art.png
Activate preferences/about window when bringing to front (fixes #111)
Fix album title color in dark style (fixes #101, thanks @Deanmv)
Update Last.fm icon in preferences
Add NSDate+TimeAgo to podfile
Add Last.fm popover that shows 10 most recent tracks
Append Last.fm icon instead of replacing other links
Add ability to love/unlove song from Last.fm popover
Add preference for showing the Last.fm button
Add preference to automatically love/unlove a track on Last.fm based on thumbs up rating (fixes #83)
Update Last.fm API keys
Fix timestamp alignment in Last.fm popover
Revert "Fix timestamp alignment in Last.fm popover"

This reverts commit 93e259c1f651ee6025f9c66f28103531fb5678db.
Remember last size of mini player (fixes #96)
Revert event tap creation, fixes QuickLook but breaks Fireworks (fixes #117)
Modify dark.css, CustomWebView to use/hold inverted sprite sheet (fixes #90, #120)

Previously, many things were made to match the dark style by using the
`-webkit-filter: invert(100%)` idiom in CSS, but this had a huge
performance impact since it was used for every thumbs up in every row,
on every player button, and so on.

To get rid of the performance hit, I instead download the sprite sheet
at the beginning of the program and invert the colors in memory. The
CSS is then updated to point to a special URL
(http://radiant-player-mac/sprites-inverted.png) at which point Radiant
Player returns the inverted image and the performance hit is now gone
as the inverted sprite sheet is now handled as a regular image.

In any forthcoming dark themes or derivatives of the built in theme, if
you need an inverted version of a particular sprite, set the
background-image to this special URL.
Fix mini player to work on OS X 10.8 (fixes #106)