Attaching new patch for unicodeobject.c, which supersedes the previous patches.

I've changed the name of the parameter of str.join() to "iterable" to match the docs. (In the previous patch I had changed it from "seq" to "iterable_of_strings".)

I also fixed two minor comments on the doc strings from Martin.

With this, AFAIK, unicodeobject.c should be good to go.