Fixed executeBase filter builder to support nulls
Fixed executeBase filter builder to support nulls

$db->quote() returns 'null' if value is_null(), but the comparer doesn't allow for this; this commit changes comparer to "IS" if value is_null()

Former-commit-id: 8160c80f83cf3896cafa17b7695512e8cf6884f1
hissy/concrete5,MrKarlDilkington/concrete5,jaromirdalecky/concrete5,mainio/concrete5,mainio/concrete5,mlocati/concrete5,mainio/concrete5,hissy/concrete5,deek87/concrete5,concrete5/concrete5,triplei/concrete5-8,haeflimi/concrete5,jaromirdalecky/concrete5,olsgreen/concrete5,deek87/concrete5,a3020/concrete5,KorvinSzanto/concrete5,MrKarlDilkington/concrete5,a3020/concrete5,rikzuiderlicht/concrete5,biplobice/concrete5,MrKarlDilkington/concrete5,acliss19xx/concrete5,jaromirdalecky/concrete5,concrete5/concrete5,mlocati/concrete5,haeflimi/concrete5,haeflimi/concrete5,concrete5/concrete5,jaromirdalecky/concrete5,deek87/concrete5,olsgreen/concrete5,biplobice/concrete5,triplei/concrete5-8,mlocati/concrete5,hissy/concrete5,hissy/concrete5,KorvinSzanto/concrete5,acliss19xx/concrete5,concrete5/concrete5,biplobice/concrete5,deek87/concrete5,rikzuiderlicht/concrete5,mlocati/concrete5,acliss19xx/concrete5,KorvinSzanto/concrete5,olsgreen/concrete5,triplei/concrete5-8,biplobice/concrete5,rikzuiderlicht/concrete5,haeflimi/concrete5