MvL accepted PEP 453! \o/
PEP 454: rationale
[PEP 451] Don't change the signature of the file-based finders.

The "Open Issues" section is also cleaned up.
Move 3.4.0a4 from future releases to released.
[PEP 451] Clarify about namespace packages and about what ModuleSpec does during loading.
[PEP 451] Fix some typos.
[PEP 451] Fix a ModuleSpec attribute (parent) that was named inconsistently in different parts.