OSMF SVN

Pre-PARB metadata changes: Eliminate StringIdentifier, it was only used by the layout package and is functionally equivalent to ObjectIdentifier. First step in the consolidation of identifier classes.

Pre-PARB metadata changes: Rename MetadataUtils to MediaTypeUtil. Make MediaTypeUtil non-public, as it's fairly trivial for clients to check for matches on their MIME type.

Pre-PARB metadata changes: Remove MimeTypes, move specific types to NetLoader where they're used.

Pre-PARB metadata changes: Remove watchFacet methods from MetadataUtils, since clients can use a MetadataWatcher directly. Update unit tests and samples accordingly.

Pre-PARB metadata changes: Hide CompositionMode, move to compositeClasses package. Convert to String-based enum pattern.

Pre-PARB metadata changes: Hide facet synthesizers from the public API, they're currently an internal affair which we can always expose later. Eliminate code where a synthesizer that matches the default synthesizer was specified. Change a few cases from NullFacetSynthesizer to the default (null may be more appropriate, but it makes the code simpler, and in most cases this is metadata that's attached to the resource and will therefore never be synthesized). Remove setElementId method from MetadatUtils, it's not used in the framework (just test code/samples), and it seems inappropriate to assume that the NullFacetSynthesizer should always be used.

Update some ASDocs.

PARB changes: Move TraitEventDispatcher to traits package. Hide URL.

PARB changes: Merge seekBegin and seekEnd event types into a single seekingChange event type. Add seeking as a getter to the SeekEvent class. Update test code and samples accordingly.

PARB changes: Convert ProxyElement.blocksTrait to a protected setter/getter of blockedTraits.