Move the *View::Presenter types, and some API into one base View.

Move the *View::Presenter types, and some API into one base View.

	* src/main/java/org/glom/web/client/ui/DetailsView.java:
	* src/main/java/org/glom/web/client/ui/DocumentSelectionView.java:
	* src/main/java/org/glom/web/client/ui/ListView.java:
	* src/main/java/org/glom/web/client/ui/TableSelectionView.java: Move
	Presenter, setPresenter() and clear() into a shared base interface,
	to avoid the unnecessary duplicate Presenter types and to more clearly
	show how the *Views share the same structure, even if they are not
	used polymorphically.

	* src/main/java/org/glom/web/client/ui/DetailsViewImpl.java:
	* src/main/java/org/glom/web/client/ui/DocumentSelectionViewImpl.ja
	va:
	* src/main/java/org/glom/web/client/activity/DetailsActivity.java:
	* src/main/java/org/glom/web/client/activity/ListActivity.java:
	* src/main/java/org/glom/web/client/activity/DocumentSelectionActiv
	ity.java:
	* src/main/java/org/glom/web/client/activity/TableSelectionActivity
	.java: Adapt.

	Feel free to revert this if there is a good reason for the duplicate
	types.