refs #768, improved selectors

* added focus proxy
* using &QLineEdit::editingFinished as signal (changes value also when focus is lost)
* use enum to set how values are displayed
* search for DB values by leveraging the smart selector functions
* added isSet functions
* minor renamings/formatting

src/blackgui/components/dbdistributorselectorcomponent.cpp

@@ -46,6 +46,7 @@ namespace BlackGui
         {
             Q_ASSERT_X(sGui, Q_FUNC_INFO, "Missing sGui");
             ui->setupUi(this);
+            this->setFocusProxy(ui->le_Distributor);
             this->setAcceptDrops(true);
             this->setAcceptedMetaTypeIds({qMetaTypeId<CDistributor>(), qMetaTypeId<CDistributorList>()});
             ui->le_Distributor->setValidator(new CUpperCaseValidator(this));