refactoring qad widgets part 1

c++ cast, nullptr, forward declaration, agregate ui, connect to member functions, order and clear includes

libs/widgets/chardialog.cpp

@@ -85,7 +85,7 @@ void CharDialog::resizeEvent(QResizeEvent * ) {
 	ui->tableChars->setColumnCount(c);
 	for (int i = 0; i < r; ++i) {
 		for (int j = 0; j < c; ++j) {
-			if (ui->tableChars->item(i, j) == 0) {
+			if (ui->tableChars->item(i, j) == nullptr) {
 				ui->tableChars->setItem(i, j, new QTableWidgetItem());
 				ui->tableChars->item(i, j)->setTextAlignment(Qt::AlignCenter);
 			}
@@ -136,7 +136,7 @@ void CharDialog::on_spinSize_valueChanged(int index) {
 	QFont font = ui->tableChars->font();
 	font.setPointSize(size);
 	ui->tableChars->setFont(font);
-	resizeEvent(0);
+	resizeEvent(nullptr);
 }