Use crc32 of filename to resume tracks

As well as using an index, which breaks when a file is added or
removed, use the crc32 of the filename. When the crc32 check passes the
index is used directly. When it fails, the slow path is taken checking
each file name in the playlist until the right crc is found. If that fails
the playlist is started from the beginning.

See http://www.rockbox.org/tracker/6411

Bump plugin API and nvram version numbers

Change-Id: I156f61a9f1ac428b4a682bc680379cb6b60b1b10
Reviewed-on: http://gerrit.rockbox.org/372
Tested-by: Jonathan Gordon <rockbox@jdgordon.info>
Reviewed-by: Jonathan Gordon <rockbox@jdgordon.info>
radio screen: Disable displaying radio art, FS#12797

With radioart enabled there appears to be buffer corruption when
the image is loaded causing the player to data abort in skin_render_line()

So, disable the code untill someone can fix it.

Change-Id: I6acf3f76ce38aa2784b1b24ed6da29a9c5bee479
Bump the plugin api version. This should have been in 212e7808.

Change-Id: I4525d62782af1ad1c0e5e92605421063b8c9b72b
Tidy up the sim x5 image by Martin Sägmüller

Change-Id: I70394e9b81964605d5af32df6dd87a8ca29c78e7
Merge branch 'master' of git://github.com/Rockbox/rockbox