Automatic imports for selected text execution

As a Groovy Console user I would like to improve execution of selected text, so that all imports of script were automatically applied to selected text.
So user will be eable to execute part of script without being forced to copy-paste import section. That would make running of a part of script much easier.
Also I think Imports from selected text should have higher priority than imports from script.

Attached patch implements changes that are required for this improvement.
Any comments are welcome!