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/transactiondesc.cpp

@@ -2,13 +2,14 @@
 
 #include "guiutil.h"
 #include "bitcoinunits.h"
-
 #include "main.h"
 #include "wallet.h"
 #include "db.h"
 #include "ui_interface.h"
 #include "base58.h"
 
+#include <string>
+
 QString TransactionDesc::FormatTxStatus(const CWalletTx& wtx)
 {
     if (!wtx.IsFinal())