finished the Preface chapter, looks ok , but I may make corrections later on. I removed a dead link and also removed tooltip icon from original PBE cause it display it in seperate space from the text so it does not work as it should. Please note also that I found a bug with todo annotation @@ it keeps outputing to html though it should not. Another thing to note as I have informed people in irc is that paragraphs do not intend as they should(space in front of them) in html output. I have also add additional info for the Pharo community like irc, and stackoverflow. I have replaced the reference to squeak source with smalltalkhub and I did some other minor corrections here and there that should be evident by the commit log.