update VTK Probe.__call__() - new ret_points argument, update docstring
update VTK Probe.__call__() - new ret_points argument, update docstring

- new .dim attribute

lokik/sfepy,rc/sfepy,rc/sfepy,vlukes/sfepy,lokik/sfepy,vlukes/sfepy,sfepy/sfepy,BubuLK/sfepy,BubuLK/sfepy,RexFuzzle/sfepy,RexFuzzle/sfepy,sfepy/sfepy,lokik/sfepy,lokik/sfepy,rc/sfepy,RexFuzzle/sfepy,vlukes/sfepy,sfepy/sfepy,RexFuzzle/sfepy,BubuLK/sfepy