fisharebest/webtrees — pull request #278 by mnoorenberghe (2014-10-19 02:26:31+00:00)
Title: Bring back deleting of user preferences

This addresses https://github.com/fisharebest/webtrees/commit/7b541d97578203274336ecb7a1d9f546b2b6e3d0#commitcomment-8211326 and brings back the old behaviour where setting a value to NULL deletes it.