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/bitcoin.qrc

@@ -1,4 +1,4 @@
-<RCC>
+<!DOCTYPE RCC><RCC version="1.0">
     <qresource prefix="/icons">
         <file alias="bitcoin">res/icons/bitcoin.png</file>
         <file alias="address-book">res/icons/address-book.png</file>