2.5 MetaBalls and UI

2.5 MetaBalls and UI

* Added callback function for some metaball properties:
When some properties (wiresize, threshold, update flags) of metaball are changed, then these properties are copied to all metaballs in the group (all metaballs with same base name). This is important to "share" some properties between metaballs, because polygonisation of metaball is influenced only by properties of base metaball and base metaball can be changed.
* Improved drawing of selected Metaball objects