View source for Krita/PaintOp Presets

We want to make brush engines presets more user visible. That means we need to make them ready for that.

The presets are saved in png files and the settings are saved as XML in png's text area.
The files saved as binary data.

Few steps that are already done:
* saving/loading works
* compatibility, version in the brush presets (Krita 2.2 presets, 2.3 presets)
* they are used for the stroke recording

Things that needs to be done:
* naming problem, name them preset1.kpp, preset2.kpp is probably bad. John sents his preset to Merry and Merry overrides her favourite preset with John's by mistake
* GHNS http://ghns.freedesktop.org/

Nice to have things:
* button in the scratchpad to create the old storke as preset for you