Bitcoin-Qt: better copyright year handling in AboutDialog

- this change allows us to keep the translation without the need to
  re-translate any string, when we update the copyright year
- copyright symbol is changed to HTML to ensure we get no encoding
  issues and it's removed from the translation string so translators don't
  break it by mistake

src/qt/aboutdialog.cpp

@@ -1,14 +1,20 @@
 #include "aboutdialog.h"
 #include "ui_aboutdialog.h"
+
 #include "clientmodel.h"
 
-#include "version.h"
+// Copyright year (2009-this)
+// Todo: update this when changing our copyright comments in the source
+const int ABOUTDIALOG_COPYRIGHT_YEAR = 2013;
 
 AboutDialog::AboutDialog(QWidget *parent) :
     QDialog(parent),
     ui(new Ui::AboutDialog)
 {
     ui->setupUi(this);
+
+    // Set current copyright year
+    ui->copyrightLabel->setText(tr("Copyright") + QString(" © ") + tr("2009-%1 The Bitcoin developers").arg(ABOUTDIALOG_COPYRIGHT_YEAR));
 }
 
 void AboutDialog::setModel(ClientModel *model)