Improve stats grid appearance

* Map day number to day of week.
* Include detailed information in cell hover-over (title) text.
* Ensure grid columns are evenly sized.
Fix stats grid colour calculations

* Add missing call of func.max() when calculating weekmax
   * This was skewing calculations by only using the maximum of the first hour rather than the whole week
* Invert colour calculation so that a white background is the norm
* Use average of red and blue channels for green channel