Cleanup code using forward declarations.

Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.

src/qt/guiutil.cpp

@@ -5,33 +5,12 @@
 #include "guiutil.h"
 
 #include "bitcoinaddressvalidator.h"
-#include "walletmodel.h"
 #include "bitcoinunits.h"
+#include "walletmodel.h"
 
-#include "util.h"
+#include "core.h"
 #include "init.h"
-
-#include <QApplication>
-#include <QDateTime>
-#include <QDoubleValidator>
-#include <QFont>
-#include <QLineEdit>
-#if QT_VERSION >= 0x050000
-#include <QUrlQuery>
-#else
-#include <QUrl>
-#endif
-#include <QTextDocument> // for Qt::mightBeRichText
-#include <QAbstractItemView>
-#include <QClipboard>
-#include <QFileDialog>
-#include <QDesktopServices>
-#include <QThread>
-#include <QSettings>
-#include <QDesktopWidget>
-
-#include <boost/filesystem.hpp>
-#include <boost/filesystem/fstream.hpp>
+#include "util.h"
 
 #ifdef WIN32
 #ifdef _WIN32_WINNT
@@ -46,9 +25,31 @@
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
-#include "shlwapi.h"
-#include "shlobj.h"
 #include "shellapi.h"
+#include "shlobj.h"
+#include "shlwapi.h"
+#endif
+
+#include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
+#include <QAbstractItemView>
+#include <QApplication>
+#include <QClipboard>
+#include <QDateTime>
+#include <QDesktopServices>
+#include <QDesktopWidget>
+#include <QDoubleValidator>
+#include <QFileDialog>
+#include <QFont>
+#include <QLineEdit>
+#include <QSettings>
+#include <QTextDocument> // for Qt::mightBeRichText
+#include <QThread>
+
+#if QT_VERSION < 0x050000
+#include <QUrl>
+#else
+#include <QUrlQuery>
 #endif
 
 namespace GUIUtil {