Add 'do not use' warning to view.setProjection

[ci skip]
Merge pull request #1146 from probins/setproj

Add 'do not use' warning to view.setProjection
Improve handling of error responses from Bing

Previously goog.asserts.assert was used to check that the response was
successful, which are stripped from compiled code.  This commit sets the
ERROR state on the source instead.
Merge pull request #1149 from twpayne/bing-maps-errors

Improve handling of error responses from Bing