devel/py-pylib: Rename to devel/py-py

• Rename py-pylib to py-py to match upstream (PyPi) name [1]
• Update to 1.4.26
• Remove DISTNAME override, no longer necessary
• Update COMMENT

Accordingly:

• Update MOVED
• Update dependents

While I'm here:

• Sort USE_PYTHON values
• Canonicalize regression-test invocations
• Make TEST_DEPENDS explicit

[1] https://pypi.python.org/pypi/py/1.4.26