Added CGateS to the __all__ list of gates
Dropped compatibility with Python 2.5
utilities: Widen isinstance() check in @public decorator
polys: Decorated classes with @public decorator
some formatting fixes in recurr.py
cleanup solvers.rst for rsolve
A bit more cleanup for recurr.py
Delete leading spaces for module documentation (recurr)
Fix typo
Replace all except Exception, e with except Exception as e
Removed min_python_version=(2, 6) from import_module() invocations
Access flags.hash_randomization with getattr() because of PyPy
fix doctest failures from changed sort key
Document integral_steps, which Gamma uses
Add doctests to integral_steps
Fix cache to work with unhashable items

The input is checked to see if it is hashable, and if it is not, it is not
cached.

We should verify that this doesn't have a major performance penalty, though I
doubt it will.
Make mutable matrices not hashable (issue 880)

I set __hash__ = None (indicating non-hashablity) on MatrixBase, meaning that
only ImmutableMatrix and ImmutableSparseMatrix should be hashable. I was not
sure if SparseMatrix was supposed to be immutable or not, but I think it is
not.
Removed unnecessary invocations of @doctest_depends_on()
Remove all `from __future__ import with_statement` lines
Use f(*args, kwarg=True) instead of f(*args, **{'kwarg':True})