Qt5 compatibility

This commit squashes all the changes in the Qt5 branch
relative to master.

Backward compatibility with Qt4 is retained.

Original authors:

- Philip Kaufmann <phil.kaufmann@t-online.de>
- Jonas Schnelli <jonas.schnelli@include7.ch>

Conflicts:
	doc/readme-qt.rst
	lebowskis-qt.pro
	src/qt/addressbookpage.cpp
	src/qt/bitcoingui.cpp
	src/qt/paymentserver.cpp
	src/qt/splashscreen.cpp
	src/qt/transactionview.cpp
	src/qt/walletframe.cpp
	src/qt/walletframe.h
	src/qt/walletstack.h
	src/qt/walletview.cpp

Conflicts:
	lebowskis-qt.pro
Look, let me explain something to you. I'm not Mr. Lebowski. You're Mr. Lebowski. I'm the Dude.

- Additional fixes to d8068b0ef2d8bb5cbba605d8a0f806ce93e8fb15 to integrate UI and slot name changes

Conflicts:
	lebowskis-qt.pro

This build with out networkhashps will not stand, man