Fix the same python 2.7.7 bug that was found in the tutorial client ages ago.
Fix some bugs.

Fixed some division issues (/ to //)

Because new style classes have __class__ behaving differently, some obfuscating code started failing, so partly migrated to a "final class" setup.

Removed a bare try-except.
Apply 2to3 to the tutorial running code.

There are still bugs in some of the tutorial runners...