Bitcoin-Qt: massive header and cpp cleanup

- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility

src/qt/signverifymessagedialog.cpp

@@ -10,11 +10,11 @@
 #include "walletmodel.h"
 #include "wallet.h"
 
+#include <QClipboard>
+
 #include <string>
 #include <vector>
 
-#include <QClipboard>
-
 SignVerifyMessageDialog::SignVerifyMessageDialog(QWidget *parent) :
     QDialog(parent),
     ui(new Ui::SignVerifyMessageDialog),