BooleanIndex not working well with radio/checkbox

[cedricmessiant]

Most of this has been fixed by 00f165c and 3ab0001 There was still a bug with counters that I fixed in the collective repository plone4 branch : https://github.com/collective/eea.facetednavigation/commit/d6828bb4fc710c9ca9ce699a612945a970790ddb

I create this issue to propose to move these conditions in the atdx_normalize function (for now, the code is duplicated in radio widget, checkbox widget and CountableWidget)