Make public iflipb variables customizable

Based on a patch from Dmitry Gutov <dgutov@yandex.ru>.
Add iflipb-permissive-flip-back setting

Based on a patch from Dmitry Gutov <dgutov@yandex.ru>.
Add license file
Prepare for version 1.1
Added tag 1.1 for changeset 51cef5b2d869