451515: Scrolling behavior of AgileGrid with very long cells 

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=451515
Apply cell-truncation code to properties view as well.
Related to Bug 451515
Merge branch 'develop' into filtersearch
Support run search in background
Better search label
first implementation of EnumFilter

empty attributes are not handled yet
Unit Tests for EnumFilter
Merge branch 'filtersearch' of ssh://git.eclipse.org:29418/rmf/org.eclipse.rmf into filtersearch
refactored fixture generation
implemented match on empty values
UnitTest implements doEmptyTest
add copyright notice