Add 'CheckIn' feature from Search GUI

[damienhaynes]

Now that we have 'Search' functionality, it makes sense for people to be able to check-in to a movie, show or episode.

Even though Scrobbling works from various plugins, it's not always possible e.g. Live TV might not have enough information to scrobble an episode, users can opt out of scrobble and instead go for the manual approach ie. search for item being watched and then checkin.

We would need to create the appropriate API methods and additional Data Structures, the context menu from Search Result windows can have an additional menu item for 'CheckIn'