changes to allow file name changing in upload, extension preserved
diff --git a/system/libraries/Upload.php b/system/libraries/Upload.php
index 92bf691..6309cae 100644
--- a/system/libraries/Upload.php
+++ b/system/libraries/Upload.php
@@ -187,7 +187,7 @@
 
 		// Set the uploaded data as class variables
 		$this->file_temp = $_FILES[$field]['tmp_name'];		
-		$this->file_name = ($this->file_name != '') ? $this->_prep_filename($this->file_name) : $this->_prep_filename($_FILES[$field]['name']);
+		$this->file_name = $this->_prep_filename($_FILES[$field]['name'];
 		$this->file_size = $_FILES[$field]['size'];		
 		$this->file_type = preg_replace("/^(.+?);.*$/", "\\1", $_FILES[$field]['type']);
 		$this->file_type = strtolower($this->file_type);
@@ -927,7 +927,13 @@
 				$filename .= '.'.$part;
 			}
 		}
-		
+
+		// file name override
+		if ($this->file_name != '')
+		{
+			$filename = $this->file_name;
+		}
+
 		$filename .= '.'.$ext;
 		
 		return $filename;