6463: fix ordering of RealInterval.a and b
RootOf: raise ValueError if no index is obtained
RootOf: _eval_Eq is defined
Relational.canonical: put symbol on lhs
FiniteSet.contains: use Eq to check inclusion

If an object defines the _eval_Eq method, it can be used
to test whether an object is not in the set.
Interval: relax test for inclusion; do symbolic reversal test
use prec with _eval_evalf, not evalf (which uses dps)
Set.as_relational: slightly simplify code
Sets: shorten line lengths
Sets: add tests
Merge pull request #8537 from smichr/ineqa

RealInterval returns correctly sorted a and b values; other misc changes
Add pep8 config, use pep8 in travis
Fix PEP 8 errors:

E111 indentation is not a multiple of four
Remove some tests from test_code_quality.py, now these run pep8