media import: add CMediaImportSource and CMediaImport
videodb: add source/import support
videodb: add seasonview and refactor GetSeasonsNav()
videodb: show friendly name of unavailable source during library clean
CVideoInfoTag: implement == and != operators and Equals()
CVideoInfoTag: implement GetDifferences()
video library: get video details on demand if they weren't loaded
video library: allow opening the info dialog for imported media items
upnp: ignore "Unknown" as a single genre as it is added by Platinum
platinum: add support for upnp:episodeCount and upnp:episodeSeason from ContentDirectory v4
platinum: add xbmc specific fields dateadded, rating, votes, studio and artwork in MediaObject

xbmc:dateadded to pass dateadded with items and not need to stat upnp resources for that
xbmc:rating for number-based rating
xbmc:votes for string-based votes number
xbmc:studio for an string-based array of studios
xbmc:artwork for a type-url-based mapping of artwork
platinum: add SearchSync method to SyncMediaBrowser
platinum: extend default browse/search filter
platinum: implement GetSearchCapabilities in media browser
upnp: set SearchCapabilities server state variable
fix GetSearchCapabilities
upnp: improve metadata reading/writing and add support for tvshows, seasons and musicvideos
upnp: fix serialization/deserialization of datetime properties
media import: add structure and logic for importing media items
media: add IMediaImportHandler implementations for movies, tvshows, seasons, episodes and musicvideos