Hide filters when table is empty

Additionally, the record set label wasn't been updated when a new record
is added or deleted.

See issue #2188 and (related) #2353

src/FilterTableHeader.cpp

@@ -128,3 +128,13 @@ void FilterTableHeader::setFilter(size_t column, const QString& value)
     if(column < filterWidgets.size())
         filterWidgets.at(column)->setText(value);
 }
+
+void FilterTableHeader::setFiltersVisible(bool visible)
+{
+    // Loop through all widgets
+    for(size_t i=0; i < filterWidgets.size(); ++i)
+    {
+        // Get the current widget, and set it visible or not
+        filterWidgets.at(i)->setVisible(visible);
+    }
+}

src/FilterTableHeader.h

@@ -15,6 +15,7 @@ public:
     explicit FilterTableHeader(QTableView* parent = nullptr);
     QSize sizeHint() const override;
     bool hasFilters() const {return (filterWidgets.size() > 0);}
+    void setFiltersVisible(bool visible);
     
 public slots:
     void generateFilters(size_t number, bool showFirst = false);

src/TableBrowser.cpp

@@ -689,6 +689,10 @@ void TableBrowser::updateRecordsetLabel()
                     (obj->type() == sqlb::Object::Table));
     }
     enableEditing(m_model->rowCountAvailable() != SqliteTableModel::RowCount::Unknown && is_table_or_unlocked_view);
+
+    // Show filters unless the table is empty
+    const bool filtersVisible = m_model->rowCount() > 0 || m_model->filterCount() != 0;
+    qobject_cast<FilterTableHeader*>(ui->dataTable->horizontalHeader())->setFiltersVisible(filtersVisible);
 }
 
 sqlb::Query TableBrowser::buildQuery(const BrowseDataTableSettings& storedData, const sqlb::ObjectIdentifier& tablename) const
@@ -1198,6 +1202,7 @@ void TableBrowser::addRecord()
         // User has to provide values acomplishing the constraints. Open Add Record Dialog.
         insertValues();
     }
+    updateRecordsetLabel();
 }
 
 void TableBrowser::insertValues()
@@ -1235,6 +1240,7 @@ void TableBrowser::deleteRecord()
     } else {
         QMessageBox::information( this, QApplication::applicationName(), tr("Please select a record first"));
     }
+    updateRecordsetLabel();
 }
 
 void TableBrowser::navigatePrevious()