This makes the rest of the attribute access fast again, but slows down
__module__.

+-------------------------------------------+------------+-------------------------------+
| Benchmark                                 | 38-master3 | 38-faster-descr               |
+===========================================+============+===============================+
| read __module__                           | 41.1 ns    | 123 ns: 2.99x slower (+199%)  |
+-------------------------------------------+------------+-------------------------------+
| read __name__                             | 41.3 ns    | 39.9 ns: 1.04x faster (-3%)   |
+-------------------------------------------+------------+-------------------------------+
| read __doc__                              | 41.8 ns    | 42.4 ns: 1.01x slower (+1%)   |
+-------------------------------------------+------------+-------------------------------+
| query adapter (no registrations)          | 3.85 ms    | 2.95 ms: 1.30x faster (-23%)  |
+-------------------------------------------+------------+-------------------------------+
| query adapter (all trivial registrations) | 4.59 ms    | 3.67 ms: 1.25x faster (-20%)  |
+-------------------------------------------+------------+-------------------------------+
| contains (empty dict)                     | 136 ns     | 54.8 ns: 2.48x faster (-60%)  |
+-------------------------------------------+------------+-------------------------------+
| contains (populated dict)                 | 137 ns     | 55.7 ns: 2.46x faster (-59%)  |
+-------------------------------------------+------------+-------------------------------+
| contains (populated list)                 | 40.2 us    | 2.86 us: 14.03x faster (-93%) |
+-------------------------------------------+------------+-------------------------------+

Not significant (1): read providedBy

On PyPy2, they are ignored (like on CPython), but on PyPy3 they can
actually be validated.

Fixes #118

Also add a line of missing whitespace.

And tox. It wasn't properly working to report coverage before.

Turns out that the C extensions build and work fine with PyPy, but don't use them by default. Let them
be forced, though.

Tests needed some refactoring to account for the various permutations.

Fixes #91

Remove many (or most) now-redundant 'pragma: no cover'.

A few minor test changes to get full branch coverage.

* Test sanity cleanups

Partially addresses #87

- Remove manual lists of tests in favor of loadTestsFromName. This
  mostly gets all test runners running the same number of tests.
- Remove `additional_tests`, which was just duplicating the discovered
  tests. No modern test runner seems to need it.
- Change the two compatibility skip decorators to actually use
  unitetest skips, which helps with the reporting.

* Per @tseaver, drop most test_suite functions.

* Port remaining doctest to unittest.

* Make the odd tests work on all supported python versions

Since we no longer support 3.2 we can use the literal syntax.

This was done with a quick sed script.

 '__code__', '__defaults__', '__func__', and '__self__' all work fine on
Python 2.6+.

We *can't* test the classAdvice stuff under Py3k.  Need to deprecate it
before the 4.0 release.