a code walkthrough of the CleanUp phase of scalac

Hi,

I've been meaning for a while to get a clearer picture of the CleanUp phase
of scalac, and as a side-effect I've drafted the attached notes to (1) offer
a tutorial for future compiler-plugin authors; and (2) share information
with those interested in learning more about the internals of scalac.
Because of these different audiences, I'm cross-posting these notes to both
the scala and scala.internals mailing lists.

Comments, extensions and corrections are welcome.

Miguel
http://www.sts.tu-harburg.de/people/mi.garcia/