Better result formatting

Cells holding a NULL value now display null in gray.
int, float and numeric columns are right aligned. Integers, floats and numerics are coloured.
Booleans, green or red for true or false. t, f is replaced by TRUE, FALSE

mainwindow.cpp

@@ -109,6 +109,8 @@ MainWindow::MainWindow(QWidget *parent)
 //	action = ui->mainToolBar->addAction("cancel");
 //	connect(action, &QAction::triggered, this, &MainWindow::cancel_query);
 
+	//ui->ResultView->setItemDelegate();
+
 	m_dbConnection.setStateCallback([this](ASyncDBConnection::State st)
 		{
 			QueueTask([this, st]() { connectionStateChanged(st); });