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/askpassphrasedialog.h

@@ -6,7 +6,6 @@
 namespace Ui {
     class AskPassphraseDialog;
 }
-
 class WalletModel;
 
 /** Multifunctional dialog to ask for passphrases. Used for encryption, unlocking, and changing the passphrase.