Skin bar tags fix+cleanup:
Don't crash when not enough params were given (i.e forgetting the filename)
Make the parser enforce the first 4 params as compulsary
Be more leniant and don't require the image filename if one isnt going to be loaded (no more need for the - as the 5th param)
Add an option "image" to specify the filename (otherwise the first option will be used if it isnt a recognised option).
e.g: %pv(0,0,100,10) or %pv(0,0,100,10, bar.bmp) or %pv(0,0,100,10, ..., image, bar.bmp)
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28247 a1c6a512-1295-4272-9138-f99709370657