add: split -> amount = amount;
context: void update_split ( struct gnucash_split * split, gchar * account, gchar * categ ){  if ( categ )    {      split -> category = g_strdup ( categ );    }  if ( account )    {      if ( !split -> account )	{	  split -> account = g_strdup ( account );	}      else	{	  split -> contra_account = g_strdup ( account );	}    }}