added qse_httpd_geterrnum()/qse_httpd_seterrnum().

added more error codes to httpd.
added qse_pio_gethandleasubi().
enhanced sample file handlers
enhanced qse_htre_completecontent()/qse_htre_discardcontent()/qse_htre_addcontent()/qse_htre_clear()
fixed many cgi handling bugs

qse/include/qse/cmn/pio.h

@@ -132,6 +132,8 @@ enum qse_pio_errnum_t
 	QSE_PIO_ECHILD,     /**< the child is not valid */
 	QSE_PIO_EINTR,      /**< interrupted */
 	QSE_PIO_EPIPE,      /**< broken pipe */
+	QSE_PIO_EACCES,     /**< access denied */
+	QSE_PIO_ENOENT,     /**< no such file */
 	QSE_PIO_ESUBSYS     /**< subsystem(system call) error */
 };
 typedef enum qse_pio_errnum_t qse_pio_errnum_t;
@@ -316,6 +318,16 @@ qse_pio_hnd_t qse_pio_gethandle (
 	qse_pio_hid_t hid  /**< handle ID */
 );
 
+/**
+ * The qse_pio_gethandleasubi() function gets a pipe handle wrapped 
+ * in the #qse_ubi_t type.
+ * @return pipe handle
+ */
+qse_ubi_t qse_pio_gethandleasubi (
+	qse_pio_t*    pio, /**< pio object */
+	qse_pio_hid_t hid  /**< handle ID */
+);
+
 /**
  * The qse_pio_getchild() function gets a process handle.
  * @return process handle