Bing Maps key changes.

 * New default Bing key (Basic / Public website).
 * Write a message to the console when this default key is used.
 * Add the ability to supply a new default Bing key (and eliminate the
message) by setting a property, in addition to optionally passing it to
the constructor as before.
Consistently call the key a key.
Merge remote-tracking branch 'origin/master' into bingKey
Show the number of messages in the Sandcastle console.

Only switch to it automatically on warnings and errors.
Remove useless line.
Merge remote-tracking branch 'origin/master' into bingKey

Conflicts:
	CHANGES.md
Removed prototype for conjugate from Quaternion
Removed prototype for magnitude and magnitudeSquared from Quaternion
Removed prototype for normalize and inverse from Quaternion
Removed prototype for add and subtract from Quaternion
Removed prototype for multiply, multiplyByScalar, and divideByScalar from Quaternion
Removed prototype for getAxis and getAngle from Quaternion
Removed prototype for lerp and slerp from Quaternion
Removed prototype for equals and equalsEpsilon from Quaternion
Removed prototype for negate and dot from Quaternion
Updated CHANGES.md
Merge remote-tracking branch 'origin/master' into bingKey
Got some missing changes
Tweak Imagery Layers Sandcastle app so it doesn't Bing-warn.
Break Bing Maps key out of the imagery provider.