View / add a constrainResolution option

This introduces a breaking change.

This options replaces the various `constrainResolution` options on interactions
and the `fit` method.

Since constraints are now the responsibility of the View, the fact that intermediary
zoom levels are allowed or not is now set in the view options.

By default, the view resolution is unconstrained.

src/ol/interaction.js

@@ -44,8 +44,6 @@ export {default as Translate} from './interaction/Translate.js';
  * focus. This affects the `MouseWheelZoom` and `DragPan` interactions and is
  * useful when page scroll is desired for maps that do not have the browser's
  * focus.
- * @property {boolean} [constrainResolution=false] Zoom to the closest integer
- * zoom level after the wheel/trackpad or pinch gesture ends.
  * @property {boolean} [doubleClickZoom=true] Whether double click zoom is
  * desired.
  * @property {boolean} [keyboard=true] Whether keyboard interaction is desired.
@@ -127,7 +125,6 @@ export function defaults(opt_options) {
   const pinchZoom = options.pinchZoom !== undefined ? options.pinchZoom : true;
   if (pinchZoom) {
     interactions.push(new PinchZoom({
-      constrainResolution: options.constrainResolution,
       duration: options.zoomDuration
     }));
   }
@@ -146,7 +143,6 @@ export function defaults(opt_options) {
   if (mouseWheelZoom) {
     interactions.push(new MouseWheelZoom({
       condition: options.onFocusOnly ? focus : undefined,
-      constrainResolution: options.constrainResolution,
       duration: options.zoomDuration
     }));
   }