[Pharo-project] little tools support to better browse the squeaktrunk

Hi all to push the closure fixes I needed to browse the squeak trunk so I added ScriptLoader new addExtraRepositories so that all the packages get their 3.9a histories and that we can in one click browse the squeak repository. As a test I will integrate some fixes done on the MC browser and other MC related features. I will document that of course in our nice bugtracker. Stef