Restore prototype equals functions to core types.

I also added data comparison options to `TimeInterval` and `TimeIntervalCollection`.

All of this is needed for `DynamicScene` Geometry & Appearances support, but I figured I'd bring it in under a separate pull to keep things manageable.
Changes after review.
Merge remote-tracking branch 'origin/master' into prototype-equals

Conflicts:
	CHANGES.md
Merge pull request #1231 from AnalyticalGraphicsInc/prototype-equals

Restore prototype equals functions to core types.