Convert Contest serial exchange to integer

some logbook programs allow for non number characters in the exchange serial number field, cloudlog would crash on import. By converting those fields to integer we probably lose some (worthless) information but still have it import correctly

application/models/Logbook_model.php

@@ -2669,11 +2669,13 @@ class Logbook_model extends CI_Model {
                 'COL_SKCC' => (!empty($record['skcc'])) ? $record['skcc'] : '',
                 'COL_SOTA_REF' => (!empty($record['sota_ref'])) ? $record['sota_ref'] : '',
                 'COL_WWFF_REF' => (!empty($record['wwff_ref'])) ? $record['wwff_ref'] : '',
-                'COL_SRX' => (!empty($record['srx'])) ? $record['srx'] : null,
-                'COL_SRX_STRING' => (!empty($record['srx_string'])) ? $record['srx_string'] : '',
+                'COL_SRX' => (!empty($record['srx'])) ? (int)$record['srx'] : null,
+                			//convert to integer to make sure no invalid entries are imported 
+				'COL_SRX_STRING' => (!empty($record['srx_string'])) ? $record['srx_string'] : '',
                 'COL_STATE' => (!empty($record['state'])) ? strtoupper($record['state']) : '',
                 'COL_STATION_CALLSIGN' => (!empty($record['station_callsign'])) ? $record['station_callsign'] : '',
-                'COL_STX' => (!empty($record['stx'])) ? $record['stx'] : null,
+						 //convert to integer to make sure no invalid entries are imported 
+                'COL_STX' => (!empty($record['stx'])) ? (int)$record['stx'] : null,
                 'COL_STX_STRING' => (!empty($record['stx_string'])) ? $record['stx_string'] : '',
                 'COL_SUBMODE' => $input_submode,
                 'COL_SWL' => (!empty($record['swl'])) ? $record['swl'] : null,