Merge pull request #942 from Codeinwp/bugfix/940

Fix temp file creation issue on instawp

Author: vytisbulkevicius

classes/Visualizer/Module.php

@@ -270,6 +270,9 @@ private function _getCSV( $rows, $filename, $enclose ) {
 
 		$bom = chr( 0xEF ) . chr( 0xBB ) . chr( 0xBF );
 		$fp = tmpfile();
+		if ( null === $fp ) {
+			$fp = fopen( wp_tempnam(), 'w+' );
+		}
 		if ( ! apply_filters( 'vizualizer_export_include_series_type', true ) ) {
 			unset( $rows[1] );
 			$rows = array_values( $rows );