OSMF SVN

Adding support for IDownloadable to ContentElements:

* Introducting ContentDownloadableTrait.
* Adding bytesLoaded and bytesTotal getters to ContentLoader. The latter fires a BytesTotalChange event, that ContentDownloadableTrait listens to.
* Updating ContentElement to instantiate the new trait.

Extending Example player:

* Adding 'bytesDownloaded:' and 'bytesTotal' fields to the UI.
* Hiding/showing the fields according to the Downloadable trait being available or not.
* Added plumbing to update the values.

Changes to previous commits:

* DownloadableTrait: CTOR: removed 'target', for we want the trait to always be the dispatcher of its own events.
* SoundDownloadableTrait: made class internal, removed 'target' from CTOR, added listener for Sound's OPEN event to ensure getting 'bytesTotal', and changing events to be dispatched on changing the value from/to NaN.
* BytesTotalChangeEvent: added 'clone' method.
* MediaPlayer: added code to start the downloadable timer on the Downloadble trait being added/removed. At 'onDownloadTimer', now also dispatching changes from/to NaN.
* BytesDownloadEvent: renamed to BytesDownloadEventChange, and made it about bytes downloaded only, using our newValue/oldValue convention. Added 'clone' method.

1. IDownloadable support
2. PluginSample is integrated with IDownloadable.as
3. unit tests fix up

Dual-buffering example: Reduce buffer size on pause.

Fix for bug FM-108 Local progressive URL not working with MediaPlayer. Modified the URL class to handle relative paths correctly.

Minor API change: Use Vector not Array for MediaElement.get traitTypes. Approved by dev team. Should be no impact to sample apps, unit tests, or test apps.

Fix brace.

Removing old prototype code.

Increasing timer interval in attempt to fix unit test on the build server.

Dual threshold buffering example: Reduce buffer time after a seek.

Refactor MediaInfo/MediaFactory relationship to make factory aspects distinct from media definitions. Remove MediaElement.initialize and all of its implementations, dynamic instantiation is now handled by a client creation function. Update all dependent code (sample apps, plugins, unit tests, etc.).