draft of natty toolchain transition guide

[Allison Randal]

I'm working on a guide to help developers/packagers make the transition 
to the new versions and default options in GCC and Python for Natty:

https://wiki.ubuntu.com/NattyNarwhal/ToolchainTransition

This is a draft, and may change while you're looking at it (I'm adding a 
section on makefiles at doko's suggestion). All comments, suggestions, 
and corrections welcome.

Allison