[scribus-dev] Soft shadows -- Partial implementation

[Benjamin Dumke-von der Ehe]

a.l.e asked me
(http://lists.scribus.net/pipermail/scribus/2012-January/045622.html)
to upload the patch for my half-baked soft shadow implementation; I
have attached it to http://bugs.scribus.net/view.php?id=3712.

It's fairly undocumented, to put it mildly -- the basic idea is the
following (as mentioned elsewhere, it only works during PDF export):

For an object that's supposed to have a soft shadow, add a 1x1 pixel
image of the shadow's color to the PDF (with /Interpolate false, so
it's really a rectangle of the desired size), and give it an /SMask
that contains a blurred version of the original object's alpha channel.

It's been a while since I wrote this, and C++ really isn't my area,
but feel free to hit me with questions; I'll try to remember what I
was thinking :)

Cheers
Ben