core, frontends: XMLUI refactoring: - now there is a base XMLUI class. Frontends inherits from this class, and add their specific widgets/containers/behaviour - wix: param.py has been removed, as the same behaviour has been reimplemented through XMLUI - removed "misc" argument in XMLUI.__init__ - severals things are broken (gateway, directory search), following patches will fix them - core: elements names in xml_tools.dataForm2XMLUI now use a construction with category_name/param_name to avoid name conflicts (could happen with 2 parameters of the same name in differents categories).