[Pharo-project] Added Class>>subclass: and Class>>subclass:instanceVariableNames:

I always missed these two methods. Class has been extended with these two methods. A new version of Kernel has been saved in PharoInbox (version 253). Note that it has been merged with Kernel- adrian_lienhard.252 http://code.google.com/p/pharo/issues/detail?id=464 Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.