Fix CesiumWidget.onRenderLoopError which was never defined.

Also add specs for onRenderLoopError to both CesiumWidget and Viewer, and clean up Viewer-related specs.
Merge pull request #1019 from AnalyticalGraphicsInc/fixWidgetErrorEvent

Fix CesiumWidget.onRenderLoopError which was never defined.
Merge pull request #987 from hpinkos/wallgeo

Make WallGeometry subsample so it matches the curvature of the ellipsoid
Change Accept header sent by loadJson.

Now sends `application/json,*/*;q=0.01` to strongly prefer JSON, but accept anything.
Merge pull request #1022 from AnalyticalGraphicsInc/fixAcceptHeader

Change Accept header sent by loadJson.
Replace `undefined` equality checks with `defined` function.

There are some errors in the conversion that still need to be addressed.
Fix remaining errors, all specs now pass.
Fix a few more find/replace errors.
Make Viewer handle data source clock management.

Previously, viewerDragDropMixin, CesiumViewer, and Sandcastle examples all had code to set the display's clock to match the first loaded data source.  Now, Viewer does that automatically by listening to the DataSourceCollection's event.

Viewer now owns its DataSourceCollection, instead of DataSourceDisplay owning it.

Also rename "Simple CZML Demo" Sandcastle example to "CZML" since there is no other CZML example anymore.
type is unnecessary.
Fix regex for detecting Cesium.js to avoid a false positive.

Add some specs to check that the regex matches expected URLs.
Changes after review.
Merge pull request #1030 from AnalyticalGraphicsInc/fixCesiumBaseUrl

Fix regex for detecting Cesium.js to avoid a false positive.
Merge branch 'master' into issue893

Conflicts:
	Source/Core/buildModuleUrl.js
Merge pull request #1029 from AnalyticalGraphicsInc/dataSourceClockManagement

Make Viewer handle data source clock management.
Merge branch 'master' into issue893

Conflicts:
	Apps/CesiumViewer/CesiumViewer.js
	Source/DynamicScene/DataSourceDisplay.js
	Source/Widgets/Viewer/viewerDragDropMixin.js
Fix bad checks due to browser differences.
Fix a few more bad checks.
Switch the last few places to use defined.
Add `FeatureDetection.supportsTypedArrays` and use it everywhere we were previously doing adhoc checks.