Enable plugins on the Sansa C200. Large parts taken from patch FS#7749 by Max Kelley...

Enable plugins on the Sansa C200. Large parts taken from patch FS#7749 by Max Kelley with tweaks, bit of cleanup and additional bitmaps by me. Some of the now enabled plugins could still be improved in regard to screen size adaptation or keymaps but this way it can easily be done later and one by one. The rather ugly 'ifndef's I added temporaryly in plugins/SOURCES will also go one by one. Plugin button actions cause some quirks in a few plugins (e.g. 'clock') but since it's not critical , the bitmaps were already done and it makes a good example for discussing plugin button actions, I thought it could go in.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14771 a1c6a512-1295-4272-9138-f99709370657