SWE-2 / SP-263: Get rid of Widget superclass

...ava/ch/systemsx/cisd/openbis/uitest/infra/Contextual.java

.../java/ch/systemsx/cisd/openbis/uitest/infra/Fillable.java

...ava/ch/systemsx/cisd/openbis/uitest/infra/Refreshing.java

...ce/java/ch/systemsx/cisd/openbis/uitest/infra/Widget.java

...stemsx/cisd/openbis/uitest/infra/webdriver/PageProxy.java

...cisd/openbis/uitest/infra/webdriver/WaitForRefreshOf.java

.../cisd/openbis/uitest/infra/webdriver/WebElementProxy.java

...cisd/openbis/uitest/infra/webdriver/WidgetWebElement.java

.../cisd/openbis/uitest/page/dialog/AddSampleTypeDialog.java

...cisd/openbis/uitest/page/dialog/EditSampleTypeDialog.java

...isd/openbis/uitest/page/tab/AssignSamplePropertyType.java

...a/ch/systemsx/cisd/openbis/uitest/page/tab/LoginPage.java

...systemsx/cisd/openbis/uitest/page/tab/RegisterSample.java

...ch/systemsx/cisd/openbis/uitest/suite/ExperimentTest.java

...cisd/openbis/uitest/suite/PropertyTypeAssignmentTest.java

...ava/ch/systemsx/cisd/openbis/uitest/suite/SampleTest.java

...a/ch/systemsx/cisd/openbis/uitest/suite/SeleniumTest.java

...ava/ch/systemsx/cisd/openbis/uitest/suite/SprintTest.java

...stemsx/cisd/openbis/uitest/type/PropertyTypeDataType.java

...a/ch/systemsx/cisd/openbis/uitest/type/Representable.java