deltasummation: Check for exactly one solution.
Raise NotImplementedError for .evalf() on indefinite integrals.

Fixes issue 3808: Calling .evalf() on indefinite integral throws an exception
http://code.google.com/p/sympy/issues/detail?id=3808
Fix test_pytest functions with the same name

raises() with a string is no longer supported, so delete those tests.
Remove unused variables from autowrap.py

The variable prototype_c has never been used since the commit that introduced
it, 2dbb3fbea27c82a669975edafd01156c245fa984.
Pyflakes on utilities

Mostly just unused names. There are still a few false positives from globals
and some logic that pyflakes can't handle.
Pyflakes on utilities tests

I left the unused imports that represented things that should be tested.

One change was a variable name typo (in code_quality). The rest were unused
variables or imports.
Remove superfluous check for tuple instance.

Limits are canonicalized to tuples by the constructor.
Pyflakes fixes for core files

These were mostly just unused imports. There was an unused branch

if isinstance(p, decimal.Decimal):
    rv =  _decimal_to_Rational_prec(p)[0]

in numbers.py.  I also found an undefined name _clear() in sympify.py that I
did not know how to handle, so I opened
https://code.google.com/p/sympy/issues/detail?id=3818 for it.
Merge pull request #2083 from jrioux/concrete

deltasummation: Check for exactly one solution.
Merge pull request #2096 from asmeurer/pyflakes

Pyflakes fixes for various parts of SymPy.
Merge pull request #2084 from jrioux/evalf

Raise NotImplementedError for .evalf() on indefinite integrals.