Attempt to parse and organize books in "series" if certain metadata tags exist

[majora2007]

If the following tags exist in an epub:
calibre:series_index
calibre:series
calibre:title_sort

then map out the book as:

Series = calibre:series
Volume = calibre:series_index
Title = calibre:title_sort

An example of this would be:
Stephen King - Dark Tower 01 - The Gunslinger
Stephen King - Dark Tower 02 - The Drawing Of The Three

These belong to a series. In each epub, you'll see:
calibre:series = Dark Tower
calibre:title_sort = The Gunslinger, The Drawing Of The Three (respectively)
calibre:series_index = 1, 2 (respectively)

This is a simple change to allow better book reading experience.