FxSQL: Fixed security filter when no instances are readable by the calling user

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@2955 d35d4baa-7912-0410-b0ae-edacad209e15
FxSQL query builder: escape search languages (to avoid using keywords such as 'is')

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@2956 d35d4baa-7912-0410-b0ae-edacad209e15
Testcase fix

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@2957 d35d4baa-7912-0410-b0ae-edacad209e15