OSMF SVN

PARB feedback: rename LayoutProperties to LayoutRendererProperties.

Pre-PARB'ing the Layout API continued:

- Internalizing layout facet classes, and
- Adding a public LayoutProperties class,
- Removing LayoutUtils (for setting properties can now be done using LayoutProperties),
- Introducing IMetadataProvider, and marking classes that have a metadata getter to be implementing it,
- Remove LayoutRendererFacet (for it can be fetched/set directly from/to the metadata easily using ObjectFacet),
- Adding LayoutRendererMode, in preparation for horizontal and vertical boxing support on the default renderer,
- Updating client code and unit tests accordingly.

Updating OMSF player to:

- Use the framework layout system to position the control bar,
- as well as for positioning the right-click overlay.

PARB feedback: Allow MediaElement subclass constructors to have default params. This involved moving the ILoader param to the second param, and providing a default when no loader is provided. For subclasses (like VideoElement) for which multiple loader types are supported, the implementation now chooses the appropriate one based on the resource type.

Updating MediaContainer-, NestedMediaContainer- and ExamplePlayer samples to work with the layout changes.

PARB changes: commenting "validateNow" with @private, and renaming containsGroup to containsChildGroup.

PARB changes: removing nesting capabilities from MediaContainer, and introducing a separate MediaContainerGroup class (that is not a MediaContainer) that now holds the functionality.

PARB changes: making "gateway" on MediaElement read-only.

Updating sample to the latest PARB changes (MediaPlayer.element to MediaPlayer.media).

PARB changes: renaming gateways to containers, renaming RegionGateway to MediaContainer, renaming HTMLGateway to HTMLMediaContainer. Renaming samples, and updating code and unit tests accordingly.