[KPhotoAlbum] Added a MoveOnCopy option to Categories.

[Andreas Neustifter]

Hi All!

I use stacks in KPA solely for different versions of a picture (RAW,
JPG, edited JPG), those are automatically stacked as they are created.

Also I use a category that tags the good and great images in a set
(selection tags), of course the tag gets moved from RAW to JPG to
edited JPG as the editing of the set progresses. (I guess that's a
pretty common work-flow.)

Problem is that all the tags are copied from RAW to JPG to edited JPG
during auto stacking so more than one version of the image gets the
selection tag (which defeats its purpose).

https://github.com/astifter/kphotoalbum-fork/commit/2363b819e3894586570f9f038fab817bbd3fe9eb
is a patch that adds an setting to each category that defines if tags
of this category are copied or moved during auto stacking (and
copying).

I really do not know if this makes sense in any way so I would really
like your input on this, I tried it and for me it works.

Thanks in advance for your feedback.

Andi