* Reduced popping effect (FS#8303)
* Scale the empty slide to average album width
* Introduced some visual settings
* Fix FS#8298 but make the criteria a screen height of less than 100 px so that only the c200 gets 50x50 slides
The scaling code is added as a lib function with a basic test plugin that's not compiled by default.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15913 a1c6a512-1295-4272-9138-f99709370657