Log Message:
Update to 3.1.1 and fix build with py-cython-0.20+.

We are happy to announce PyTables 3.1.1.

This is a bug-fix release that addresses a critical bug that make PyTables
unusable on some platforms.

What's new
==========

- Fixed a critical bug that caused an exception at import time.
  The error was triggered when a bug in long-double detection is detected
  in the HDF5 library (see :issue:`275`) and numpy_ does not expose
  `float96` or `float128`. Closes :issue:`344`.
- The internal Blosc_ library has been updated to version 1.3.5.
  This fixes a false buffer overrun condition that made c-blosc to fail,
  even if the problem was not real.

As always, a large amount of bugs have been addressed and squashed as well.