[Pharo-project] [code review needed] first iteration on moving fileIn users to new codeImporter

http://code.google.com/p/pharo/issues/detail?id=5819 - some cleanings to fileIn usages - some fileIn users moved to use CodeImporter - some fixes to the CodeImporter that raised when testing the two points of above. -- Marcus Denker -- http://marcusdenker.de