Add statistics

[The4thLaw]

Summary
Demyo 1 had statistics, it would be good if Demyo 3 had some as well.

Describe the feature you'd like
Some relevant statistics to be computed would be

• General statistics (it would be nice to present this with a sentence like "You own XX albums
  • Number of series, albums, one shots (excluding the wishlist)
  • Number of albums in the wishlist
  • Number of publishers and collections
  • Number of authors
  • Number of derivatives, types and sources
  • Number of tags
  • Number of images
• Album statistics
  • Top 5 series in album count
  • Top 5 series in current worth
  • Number of purchases per year, with a drill-down on months
  • Value of purchases per year, with a drill-down on months
  • Net value of the whole collection
• Authors statistics
  • Most prolific authors per role (Top 5), assuming that role represents at least 10% (or some other factor) of the authors
  • Distribution by role (exluding roles with 0 author)
• Publisher statistics
  • Most productive publishers
  • Drill-down per collection (with a "no collection" option)
• Derivative statistics
  • Most productive sources (Top 5, possible to display everything)
  • Most represented types (Top 5, possible to display everything)
  • Net value of the whole collection, drill-down per type
  • Number of purchases per year, with a drill-down on months
  • Value of purchases per year, with a drill-down on months