Warning message won't appear when no elements are selected upon - remove
selected in test cases viewer.
Added WarningModelOperations. Because it has methods which alter model
and might result in warning. Couldn't come up with better name, sorry.
Added several warnings upon pasting.
Added warnings upon changing expected status of category.
Removing validation & warning code from this class and shifting it to
WarningModelOperations.
Merge branch 'dev-abstract_models' of
https://github.com/testify-no/ecFeed.git into dev-abstract_models

Conflicts:
	ecfeed/src/com/testify/ecfeed/ui/editor/ParametersViewer.java