OSMF SVN

PARB changes: Remove references to URL within metadata APIs, where Strings would suffice.

Fix some stray references to TemporaProxyElement and the old package structure.

PARB changes: Rename PluginLoadEvent to PluginManagerEvent.

PARB changes: Refactor MediaFactory and Loader classes:
- MediaInfo becomes MediaFactoryItem. All MediaFactory and plugin-related APIs are updated accordingly. The rule of thumb is to use "item" on MediaFactory, and "mediaFactoryItem" on the plugin classes (since the former are already qualified, whereas the latter are not).
- Remove IMediaResourceHandler. Add canHandleResource to LoaderBase. Make handler function a Function to pass to MediaFactoryItem's constructor.
- Merge resolver interfaces/classes into MediaFactoryItemResolver, which defaults to selecting the first one.
- Make LoaderBase load/unload methods final. Add protected methods to execute the load, so that we can ensure validation takes place first.
- Update all unit tests and sample apps accordingly.

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.

Removed build warnings from several test projects.

Changed element -> mediaElement.

Update build-config files for sample plugins.

Update project files for sample apps.

IMediaResource - > MediaResourceBase.
IURLResource -> Gone.