Fixed the top left link and changed the homepage

* The homepage has had the following changes:
  - Image credits removed (no more imagesto give credit for)
  - `Report a Bug' section fixed, with a section added for reporting
    errors in data.
  - More examples of the filter
  - Explanation of the `Caught Pokemon' frature.

* Changed the stylesheet to move the contents of table cells to the
  middle of the cell.

* The link in the top left of the page goes to the homepage now, as
  opposed to nowhere.