Fix issue #64

Modify regular expression to be able to handle SQL bracket delimiters for
column names that contain special characters or SQL keywords.

Signed-off-by: Hamza Bhatti <tiyowan@gmail.com>
diff --git a/system/database/DB_active_rec.php b/system/database/DB_active_rec.php
index eaae23f..f648e55 100644
--- a/system/database/DB_active_rec.php
+++ b/system/database/DB_active_rec.php
@@ -341,7 +341,7 @@
 		$this->_track_aliases($table);
 
 		// Strip apart the condition and protect the identifiers
-		if (preg_match('/([\w\.]+)([\W\s]+)(.+)/', $cond, $match))
+		if (preg_match('/([\[\w\.]+)([\W\s]+)(.+)/', $cond, $match))
 		{
 			$cond = $this->_protect_identifiers($match[1]).$match[2].$this->_protect_identifiers($match[3]);
 		}