qt: GUI for conflicted transactions

- Exclamation mark icon for conflicted transactions
- Show mouseover status for conflicted transactions as "conflicted"
- Don't show inactive transactions on overview page overview

src/qt/transactionfilterproxy.h

@@ -36,6 +36,9 @@ public:
     /** Set maximum number of rows returned, -1 if unlimited. */
     void setLimit(int limit);
 
+    /** Set whether to show conflicted transactions. */
+    void setShowInactive(bool showInactive);
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const;
 
 protected:
@@ -48,6 +51,7 @@ private:
     quint32 typeFilter;
     qint64 minAmount;
     int limitRows;
+    bool showInactive;
 };
 
 #endif // TRANSACTIONFILTERPROXY_H