ABI fix, call getFilterOptions with the correct amount of parameters.
Correctly determine filters and presets in Frontend lists. Fixes #48.
fixing filter option URL generating, fixes #49.
Streamlined class WidgetTags.
Now the options are generated with a subroutine which does also honor the attributes like "onchange" etc.
Added new filter rule MetaModelFilterRuleAND for AND conditions.
Added phpdoc comments to MetaModelFilterRuleOR
Another huge step in frontend filters.