inset-forall: clear selection after each action

This avoid a crash when doing
  command-sequence inset-forall Caption char-delete-forward; statistics; undo
in the user guide when a malformed selection is created.

The selection happens here because char-delete-forward will select the
caption instead of deleting it if the "force" parameter is not given.
This is a poor API IMO, it is the plain <del> action that should use a
special parameter.

src/BufferView.cpp

@@ -2081,6 +2081,8 @@ void BufferView::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 				if (insname == name || name == from_utf8("*")) {
 					curs.recordUndo();
 					lyx::dispatch(fr, dr);
+					// we do not want to remember selection here
+					curs.clearSelection();
 					++iterations;
 					break;
 				}