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.h

@@ -3,7 +3,6 @@
 
 #include <QString>
 #include <QObject>
-#include <string>
 
 class CWallet;
 class CWalletTx;
@@ -13,8 +12,10 @@ class CWalletTx;
 class TransactionDesc: public QObject
 {
     Q_OBJECT
+
 public:
     static QString toHTML(CWallet *wallet, CWalletTx &wtx);
+
 private:
     TransactionDesc() {}