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/transactiontablemodel.cpp

@@ -4,24 +4,27 @@
 
 #include "transactiontablemodel.h"
 
-#include "guiutil.h"
-#include "transactionrecord.h"
-#include "guiconstants.h"
-#include "transactiondesc.h"
-#include "walletmodel.h"
-#include "optionsmodel.h"
 #include "addresstablemodel.h"
 #include "bitcoinunits.h"
+#include "guiconstants.h"
+#include "guiutil.h"
+#include "optionsmodel.h"
+#include "transactiondesc.h"
+#include "transactionrecord.h"
+#include "walletmodel.h"
 
+#include "main.h"
+#include "sync.h"
+#include "uint256.h"
+#include "util.h"
 #include "wallet.h"
-#include "ui_interface.h"
 
-#include <QList>
 #include <QColor>
-#include <QTimer>
-#include <QIcon>
 #include <QDateTime>
 #include <QDebug>
+#include <QIcon>
+#include <QList>
+#include <QTimer>
 
 // Amount column is right-aligned it contains numbers
 static int column_alignments[] = {