Initial support to decode old, ambiguous data files, missing an encoding declaration, with the help of the user.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@13781 57a11ea4-9604-0410-9ed3-97b8803252fd

lib/libqof/qof/qofbackend.h

@@ -116,6 +116,7 @@ typedef enum {
   ERR_FILEIO_BACKUP_ERROR,   /**< couldn't make a backup of the file */
   ERR_FILEIO_WRITE_ERROR,    /**< couldn't write to the file */
   ERR_FILEIO_READ_ERROR,     /**< Could not open the file for reading. */
+  ERR_FILEIO_NO_ENCODING,    /**< file does not specify encoding */
 
   /* network errors */
   ERR_NETIO_SHORT_READ = 2000,  /**< not enough bytes received */

lib/libqof/qof/qofsession.c

@@ -1113,6 +1113,7 @@ qof_session_load (QofSession *session,
 	err = qof_session_get_error(session);
 	if ((err != ERR_BACKEND_NO_ERR) &&
 		(err != ERR_FILEIO_FILE_TOO_OLD) &&
+		(err != ERR_FILEIO_NO_ENCODING) &&
 		(err != ERR_SQL_DB_TOO_OLD))
 	{
 		/* Something broke, put back the old stuff */