Don't invoke interactions if view is not defined
Make View2D-only comments more consistent
Use view2DState in ol.interaction.Drag
Use view2DState in ol.interaction.DragPan
Use view2DState in ol.interaction.DragRotateAndZoom
Use view2DState in ol.interaction.DragRotate
Use view2DState in ol.interaction.TouchPan
Use view2DState in ol.interaction.TouchRotate
Use view2DState in ol.interaction.TouchZoom
Merge pull request #820 from twpayne/use-view2dstate-in-interactions

Use view2DState in interactions