Show 'export' link only if allowed.
Add <br/> to attachments#index if no attachments present.
This improves the layout a bit.
Improve authorization of data export.
Update todo.txt
Display '<empty>' instead of 'data error?' in _instancevalue_string partial in
case of nil data_string field.
Add corresponding unit tests.
Add new versions of some instancevalueset views.
Fix layout in PH_PA_Chiller detailed view.
Update todo.txt
Add missing (dummy) views for PH_VacuumControl version 5.
Update todo.txt