rename 'pbcoreDescriptionDocument' to 'asset'
change documentation references from 'DescriptionDocument' to 'asset'
change both 'pbcoreInstantiationDocument' and 'pbcoreInstantiation' to simply 'instantiation'
remove lots of redundant expression of context from element names [warning: lots of renamed elements]
change internal version attribute

this isn't version 2.0RC1 anymore
remote readability comments that end sections without starting them
consolidante documentation on 'date'
make titleStringType more generic (renamed to 'string_w_type')
consolidate string_w_type and subjectStringType

also specify type="xsd:string" with the type attribute
clarify the difference between pbcoreCreator and creator, renamed to creator and name, same for contributor and publisher
change expression 'media item' to 'asset'

since 'asset' is defined within the schema but 'media item' isn't.
consolidate schéma documentation on 'annotation'
fixing spelling errors, confusing mixes of 'media item', 'asset' and 'instantiation', removing "smart" quotes
remove empty lines for consistency