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.h

@@ -8,11 +8,12 @@
 #include <QAbstractTableModel>
 #include <QStringList>
 
-class CWallet;
-class TransactionTablePriv;
 class TransactionRecord;
+class TransactionTablePriv;
 class WalletModel;
 
+class CWallet;
+
 /** UI model for the transaction table of a wallet.
  */
 class TransactionTableModel : public QAbstractTableModel