Tutorial update for 3.0 by Paul Dubois.

I had to fix a few markup issues in controlflow.rst and modules.rst.

There's a unicode issue on line 448 in introduction.rst that someone else needs to fix.
diff --git a/Doc/tutorial/interactive.rst b/Doc/tutorial/interactive.rst
index 8eeca2a..11a970f 100644
--- a/Doc/tutorial/interactive.rst
+++ b/Doc/tutorial/interactive.rst
@@ -158,6 +158,8 @@
 symbol table.  A command to check (or even suggest) matching parentheses,
 quotes, etc., would also be useful.
 
+.. %
+   Do we mention IPython? DUBOIS
 
 .. rubric:: Footnotes