changed class instantiations to reference global $LANG and fetch existing Exceptions class, and added language variable for database error heading

http://codeigniter.com/bug_tracker/bug/4421/
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index be5c8c9..c523165 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -139,6 +139,7 @@
 	<li>Fixed a bug in the table library that could cause identically constructed rows to be dropped (#3459).</li>

 	<li>Fixed a bug (#4206) in the Directory Helper where the directory resource was not being closed, and minor improvements.</li>

 	<li>Fixed a bug where SMTP emails were not having dot transformation performed on lines that begin with a dot.</li>

+	<li>Fixed a bug in display_error() in the DB driver that was instantiating new Language and Exception objects, and not using the error heading.</li> 

 </ul>

 

 <h2>Version 1.6.1</h2>