Lute v3

Feature changes:

• #405: add UserSetting for book stats sample size.

There was a big refactor/rewrite of much of the book stats calculation code. The calculation isn’t instantaneous, but as the graphs are ajaxed in now, it should suffice.

Tweaks:

• Show term popup if parent is set.
• Ajax in book stats on home page for speed.
• Simplify datatables rendering.

Fixes:

• #487: Use term IDs for deletes.
• #488: Handle Japanese “repeat” kanji character.