cse hanlding of IndexedBase
Added test for cse of Indexed instances
Revert "cse hanlding of IndexedBase"

This reverts commit a574d35bd7916ba7bb30eff731984e6d6afd493e.
Added NotIterable mixin class, added same to default exclude tuple in iterable()
Added NotIterable to parents of tensor.IndexedBase (enables cse)
Tidying up of test_cse.
Added tests for iterable() on Indexed and MatrixSymbol, added xfail test of cse on matrixexpr
Extended docstring of iterable() and NotIterable
Reverted NotIterable mixin of MatrixExpr
Reverted test for iterable(MatrixExpr())
Made DeferredVector NotIterable and added test for it
Removed lint print statement in test
Update year in citation templates
Remove try/except block for fractions import
Use float.as_integer_ratio (we don't support py2.5 anymore)
import isgeneratorfunction() from inspect module
Fix Wigner Issue: float arguments to range() in gaunt(), racah(), wigner_9j()
Test structural equality in fallback(): partial fix for gh issue 2877
Enable hack2 for _subs to workaround Mul autoevaluation

    fixes #2877
Merge pull request #2880 from skirpichev/misc

Misc fixes