Fixing indefinite growth of state file on consecutive load and saves.

There were three issues broadly relating with animation which caused
this behavior.

1. Issue with multiple RepresentationHelperProxies being saved.
	 - This was solved by deleting the older proxies.

2. Multiple TimeAnimationCue proxies were also being created.
	 - We make sure that a single TimeAnimationCue proxy is reused.

3. TimeKeeper proxy has multiple sources and cause segfaults on
   consequent loading and saving of state files.
   - TimeKeeper triggered the loading of the source and view proxies
	 when the same source/view is was being loaded by the state-loading
	 mechanism. This causes duplicate entries and race conditions. The
	 solution is to make the TimeKeeper not trigger anything when the
	 state file is being loaded.

Change-Id: I7d9dae4f5a7321b6739d8f5c36a983605d979845
Merge topic '0013365-huge-state-file' into next

fa5d6b9 Fixing indefinite growth of state file on consecutive load and saves.