Migration to CakePHP 1.3

CakePHP 1.3 is supposed to perform better, so this should speed up Tatoeba.

Please checkout this branch and thoroughly test it. (Don’t forget to run the SQL update script.)

To check for migration bugs, I did a recursive download of both master and this branch, and then used `diff -r` to track changes. So I only carefully checked pages that are visible while being logged out. I only checked the logged in things with my eyes, and tested the usual POST actions for sentences, comments, tags, user profile and preferences, and the wall.