Replace native bookmarks with custom bookmarks.

This is all the resume code. IT's been tested using sqlite pretty extensively, but not with MySQL at all. There are some somewhat strange changes to work around XBMC bugs so let me know if you have any questions.

One big benefit of this code is that the same bookmarks work across all instances of a movie/episode (i.e. strm file, recently added, in the plugin itself, some episode/movie played from different places in the plugin).