Updates class autoloader to use class_alias

Makes Exceptions extend the base classes, rather than the subclasses to
avoid class redefinition errors.
Makes PluginFactories define the interface using the base class rather
than a subclass to avoid class_implements() to fail by testing for a
class not in the hierarchy.

source/lib/SihnonFramework/Log/PluginFactory.class.php

@@ -3,7 +3,7 @@
 class SihnonFramework_Log_PluginFactory extends Sihnon_PluginFactory {
     
     protected static $plugin_prefix    = 'Sihnon_Log_Plugin_';
-    protected static $plugin_interface = 'Sihnon_Log_IPlugin';
+    protected static $plugin_interface = 'SihnonFramework_Log_IPlugin';
     protected static $plugin_dir       = array(
     	SihnonFramework_Lib => 'SihnonFramework/Log/Plugin/',
     	Sihnon_Lib          => 'Sihnon/Log/Plugin/',