Use live bound object for imagery array, remove context.imagery() accessor

Also update documentation, closes #3359

modules/core/context.js

@@ -259,13 +259,6 @@ export function coreContext() {
     };
 
 
-    /* Imagery */
-    context.imagery = function(_) {
-        background.load(_);
-        return context;
-    };
-
-
     /* Container */
     var container, embed;
     context.container = function(_) {
@@ -347,7 +340,7 @@ export function coreContext() {
     context.reset = context.flush = function() {
         context.debouncedSave.cancel();
         _.each(services, function(service) {
-            if (typeof service.reset === 'function') {
+            if (service && typeof service.reset === 'function') {
                 service.reset(context);
             }
         });
@@ -407,10 +400,11 @@ export function coreContext() {
     context.zoomOutFurther = map.zoomOutFurther;
     context.redrawEnable = map.redrawEnable;
 
+    background.init();
     presets = presetInit();
 
     _.each(services, function(service) {
-        if (typeof service.init === 'function') {
+        if (service && typeof service.init === 'function') {
             service.init(context);
         }
     });

modules/renderer/background.js

@@ -1,10 +1,11 @@
 import * as d3 from 'd3';
 import _ from 'lodash';
-import { utilRebind } from '../util/rebind';
+import { data } from '../../data/index';
 import { geoExtent, geoMetersToOffset, geoOffsetToMeters} from '../geo/index';
-import { utilQsString, utilStringQs } from '../util/index';
 import { rendererBackgroundSource } from './background_source';
 import { rendererTileLayer } from './tile_layer';
+import { utilQsString, utilStringQs } from '../util/index';
+import { utilRebind } from '../util/rebind';
 
 
 export function rendererBackground(context) {
@@ -191,7 +192,7 @@ export function rendererBackground(context) {
     };
 
 
-    background.load = function(imagery) {
+    background.init = function() {
         function parseMap(qmap) {
             if (!qmap) return false;
             var args = qmap.split('/').map(Number);
@@ -199,12 +200,13 @@ export function rendererBackground(context) {
             return geoExtent([args[1], args[2]]);
         }
 
-        var q = utilStringQs(window.location.hash.substring(1)),
+        var dataImagery = data.imagery || [],
+            q = utilStringQs(window.location.hash.substring(1)),
             chosen = q.background || q.layer,
             extent = parseMap(q.map),
             best;
 
-        backgroundSources = imagery.map(function(source) {
+        backgroundSources = dataImagery.map(function(source) {
             if (source.type === 'bing') {
                 return rendererBackgroundSource.Bing(source, dispatch);
             } else {

modules/svg/debug.js

@@ -1,9 +1,9 @@
 import * as d3 from 'd3';
 import { geoPolygonIntersectsPolygon } from '../geo/index';
 import {
+    data,
     dataImperial,
-    dataDriveLeft,
-    dataImagery
+    dataDriveLeft
 } from '../../data/index';
 
 
@@ -83,6 +83,7 @@ export function svgDebug(projection, context) {
 
 
         var extent = context.map().extent(),
+            dataImagery = data.imagery || [],
             availableImagery = showsImagery && multipolygons(dataImagery.filter(function(source) {
                 if (!source.polygon) return false;
                 return source.polygon.some(function(polygon) {