Added explain functionality.

Uses json format with jsoncpp as a parser. Then show it in a QTreeView.
Shows inclusive/exclusive times like explain.despesz does. Also a similar
coloring scheme as applied.

PgsqlConn.h

@@ -10,6 +10,7 @@
 
 namespace Pgsql {
 
+	class Connection;
 	/*
 	This library has multiple layers.
 
@@ -31,6 +32,29 @@ namespace Pgsql {
 
 	};
 
+	class ErrorDetails {
+	public:
+		static ErrorDetails createErrorDetailsFromPGresult(const PGresult *res);
+
+		std::string state; ///< PG_DIAG_SQLSTATE Error code as listed in	https://www.postgresql.org/docs/9.5/static/errcodes-appendix.html
+		std::string severity;
+		std::string messagePrimary;
+		std::string messageDetail;
+		std::string messageHint;
+		int statementPosition; ///< First character is one, measured in characters not bytes!
+		int internalPosition;
+		std::string internalQuery;
+		std::string context;
+		std::string schemaName;
+		std::string tableName;
+		std::string columnName;
+		std::string datatypeName;
+		std::string constraintName;
+		std::string sourceFile;
+		std::string sourceLine;
+		std::string sourceFunction;
+	};
+
 	/** Non-copyable but movable wrapper for a postgresql result. */
 	class Result {
 	public:
@@ -76,8 +100,19 @@ namespace Pgsql {
 		operator bool() const;
 
 		ExecStatusType resultStatus();
+
 		std::string getResStatus();
 
+		/** Use this to retrieve an error code when this is an error result
+		 *
+		 * The possible code are listed in https://www.postgresql.org/docs/9.5/static/errcodes-appendix.html
+		 */
+		std::string diagSqlState();
+		/** Retrieves all the error fields. */
+		ErrorDetails diagDetails();
+
+
+
 
 		int getRows() const;
 		int getCols() const;
@@ -91,6 +126,21 @@ namespace Pgsql {
 		PGresult *result = nullptr;
 	};
 
+
+	class Canceller {
+	public:
+		Canceller(PGcancel *c);
+		Canceller(const Canceller&) = delete;
+		Canceller& operator=(const Canceller&) = delete;
+		Canceller(Canceller&& rhs);
+		Canceller& operator=(Canceller&& rhs);
+		~Canceller();
+		void cancel();
+	private:
+		PGcancel *m_cancel;
+	};
+
+
 	class Connection {
 	public:
 		Connection();
@@ -120,6 +170,7 @@ namespace Pgsql {
 		int socket();
 
 		void close();
+		Canceller getCancel();
 
 		std::string getErrorMessage() const;
 
@@ -140,15 +191,14 @@ namespace Pgsql {
 		bool consumeInput();
 		bool isBusy();
 
-
+		void setNoticeReceiver(std::function<void(const PGresult *)> callback);
 	private:
 		PGconn *conn = nullptr;
+		std::function<void(const PGresult *)> notifyReceiver;
+
+		static void notifyReceiveFunc(void *arg, const PGresult *result);
 	};
 
-	class Canceller {
-	public:
-		void Cancel();
-	};