move all exception declaration to their own file

lib/AudioBook.php

@@ -2,12 +2,6 @@
 
 require_once('DbMapping.php');
 
-class BookNotFoundException extends WebException {
-    public function __construct($code) {
-        parent::__construct('BookNotFound', "The book with code $code was not found", -404);
-    }
-}
-
 /**
  * AudioBook is mapped on a Notice from NetBiblio
  *

lib/Connection.php

@@ -52,22 +52,6 @@ class Connection
     final private function __clone() {}
 }
 
-class SqlException extends Exception
-{
-    private $query;
-
-    public function __construct($message = "Sql Error", $query = "")
-    {
-        $this->query = $query;
-        parent::__construct($message, 0);
-    }
-
-    public function getSqlError()
-    {
-        return $this->getMessage().' while executing: '.$this->query;
-    }
-}
-
 class OdbcResultSet implements Iterator, ArrayAccess
 {
     public $length;

lib/DbMapping.php

@@ -120,9 +120,3 @@ abstract class DbMapping
         return $result;
     }
 }
-
-
-/**
- * Exception raised when an invalid attribute name is accessed
- */
-class InvalidAttributeException extends Exception { }