e widget bgpreview - stop using livethumb as it cuases performance issues
e widget bgpreview - stop using livethumb as it cuases performance issues

bgp[review uses livethumb. livethumb by definition uses an image
canvas with a sw engine and thus not only renders the bg with another
engine, it also is causing continual texture uploads thanks to the
pager and this shows clearly on slow systems. this causes memory
duplication for the same wallpaper as ever bg has its own canvas and
buffer etc.

this does come with a quality drop though and that's up for debate. we
COULD use something else like a proxy or map in between to force a
higher "virtual" res vs output. but for now at least this solves both
a memory bloat issue and a performance problem.

@fix

tasn/enlightenment,tasn/enlightenment,tasn/enlightenment