Add a runtime failure function
Tidy up the member code. Add a modify guard class around static notifications.
Move the StaticModifyGuard to the header so that atom module can use it.
Add a public notify method to dispatch to the observers.

Fix a few recount leaks
Update module constants
Minor cleanup and better choice of names.
Update the __sizeof__ computation
Remove no longer used files
Expose public (un)observe methods.

Move the notification dispatching to an external file.
Handle the work of notification dispatching.

Put the allocation of the MemberChange object on a freelist.
Add Member subclasses Event and Signal
Add Event and Signal into the import module
Update Python files for the new C++ api.

This also updates the AtomMeta class to support more features.
Update the build script
Fix a refcount bug when validation raises an exception
Add an Instance validator
Add Instance and Typed member definitions