[DONE] * fix parser, there are still crazy cases where we do not parse notes and separators correctly (multi-line notes)
[DONE] * add support for missing parameters (int, float, choice, note supported)
* add support for layer modes: so far current layer is filtered
    * modes like current layer+above, all visible, etc.
* UNDO does not work correctly sometimes
* implement preview and it's modes
* implement progress
* figure out on-line updates for filter defintions
* separate included gmic code to stand-alone library and link dynamically 

