Windows Executable File Object/PEResourceTypeEnum and related Fixes

Multiple changes related to the PEResourceTypeEnum:

*Added MessageTableEntry value to PEResourceTypeEnum
*Normalized/added annotations to values in PEResourceTypeEnum (some were missing).
*Added PEResourceContentType - union of xs:string and PEResourceTypeEnum. Set Type field in PEResourceType to use this new type.
*Normalized/updated annotations in entire file for consistency.

This should close issue #65.