Execute SQL tab: Add search bar for SQL code #191

The find operations in QScintilla are used for implementing a find frame
in the SQL Editor of the main window. A checkable tool button is added
in the SQL Editor toolbar for showing and hiding this frame.

There are check boxes for Whole Words, Case Sensitive and Regular
Expressions. The QScintilla facilities in the findFirst method are used
for the implementation.

src/MainWindow.cpp

@@ -2634,3 +2634,9 @@ void MainWindow::renameSqlTab(int index)
     if(!new_name.isNull())      // Don't do anything if the Cancel button was clicked
         ui->tabSqlAreas->setTabText(index, new_name);
 }
+
+void MainWindow::setFindFrameVisibility(bool show)
+{
+    qobject_cast<SqlExecutionArea*>(ui->tabSqlAreas->currentWidget())->setFindFrameVisibility(show);
+
+}