Fixed three bugs and add a feature to KisFilterOp

1) Fixed painting on semi-transparent images. Now COMPOSITE_COPY is the
default mode and it works nicely!
2) Added a feature: Smudge Mode for the Filter Op. The temporary device is
not cleared every time, which creates really nice effects.
3) Fixed loading of the default filter configuration for the Filter Op
4) Fixed an offset bug when painting with Gaussian Blur.



M +- -- krita/plugins/paintops/defaultpresets/filter.kpp