use QSocketNotifier, not poll...
use QSocketNotifier, not poll
avoids having to disable App Nap outright.
Also use appnope context manager to disable App Nap on OS X 10.9 while processing events.
Adds IPKernel._darwin_app_nap flag, so that working with App Nap can be disabled, in case appnope causes problems for some.
App Nap is just disabled outright on wx.