SmoothlifeInstance -> Instance
Removed Iris
Add MessageHandler and msg::* functions.

These replace the Instance::Message* functions, which were ugly.
Clean up instance.{cc,h} a little.

* Remove Instance::sim_size_
* Remove unused headers
* Macro for messages
* Remove enter key => fullscreen
Reorder functions in messages.{cc,h}
Switch to using pepper_canary
Add ARM build.

I had to use fftw-3.2.2 for arm, fftw-3.3.2 failed when compiling with
arm-nacl-gcc
(https://code.google.com/p/nativeclient/issues/detail?id=3205).