Merge remote-tracking branch 'upstream/master' into vector-api

Conflicts:
	src/objectliterals.jsdoc
	src/ol/attribution.js
	src/ol/geom/geometry.js
	src/ol/geom/geometrycollection.js
	src/ol/geom/linestring.js
	src/ol/layer/vectorlayer.exports
	src/ol/layer/vectorlayer.js
	src/ol/map.js
	src/ol/proj/proj.js
	src/ol/renderer/canvas/canvasvectorlayerrenderer.js
	src/ol/source/imagewmssource.js
	src/ol/source/tilewmssource.js
	src/ol/source/vectorsource.exports
	src/ol/source/vectorsource.js
	src/ol/source/wmssource.js
	src/ol/style/style.js
	src/ol/tilegrid/tilegrid.js
	src/ol/tilegrid/wmtstilegrid.js
	src/ol/tilegrid/xyztilegrid.js
Use olx options ns in icon and geojson examples
ol.render.DragBox renamed to ol.render.Box
Use better type
Rename a property
ol.render.Box refactoring
Add ol.interaction.DragBox
Make DragZoom interaction inherit from DragBox
Rename drag zoom interaction exports file
No default style in ol.render.Box
Add style option to DragBox interaction
Add style option to DragZoom interaction
Show how to use DragBox interaction (to remove)