Get the encoding name from a combo box in the "Set encoding" dialog

User can enter the encoding name with completion or select it from the
list using the mouse. This will help users to discover available codecs
and to find a suitable one in an easier way. This should help with encoding
issues like #1453.

src/MainWindow.cpp

@@ -25,6 +25,7 @@
 #include "RemoteDock.h"
 #include "RemoteDatabase.h"
 #include "FindReplaceDialog.h"
+#include "Data.h"
 
 #include <QFile>
 #include <QApplication>
@@ -2773,15 +2774,20 @@ void MainWindow::browseDataSetTableEncoding(bool forAllTables)
     // Ask the user for a new encoding
     bool ok;
     QString question;
+    QStringList availableCodecs = toStringList(QTextCodec::availableCodecs());
+    availableCodecs.removeDuplicates();
+    int currentItem = availableCodecs.indexOf(encoding);
+
     if(forAllTables)
         question = tr("Please choose a new encoding for all tables.");
     else
         question = tr("Please choose a new encoding for this table.");
-    encoding = QInputDialog::getText(this,
+    encoding = QInputDialog::getItem(this,
                                      tr("Set encoding"),
                                      tr("%1\nLeave the field empty for using the database encoding.").arg(question),
-                                     QLineEdit::Normal,
-                                     encoding,
+                                     availableCodecs,
+                                     currentItem,
+                                     true, // editable
                                      &ok);
 
     // Only set the new encoding if the user clicked the OK button