CRM-15609 Between date filter does not work in views, if inside an OR block

I have changed the op_between function to work more like the overriden function from views_handler_filter_date. This generates the correct SQL for me.
Merge pull request #190 from tisoft/patch-1

CRM-15609 Between date filter does not work in views, if inside an OR block
Merge remote-tracking branch 'upstream/7.x-4.5' into 7.x-4.5-7.x-master-2014-11-24-15-59-11