Return TypeError for comparisons, if self is not a real
Remove relational tests
Fix test_relational_noncommutative
Fix test_inverse_laplace_transform
Merge branch 'master' into I-comp
Fix test_partial_simp
Merge pull request #7792 from skirpichev/I-comp

Return TypeError for comparisons, if self is not a real
consolidate _eval_power processing from exp into Pow

The two routines should almost be the same but they weren't. Now
exp (except for some special cases as a function) defers to Pow's
version of _eval_power. Some slight differences are now seen in
test results.
allow large exponents to join in (x**y)**z, also when z=1/2
limit polar processing to base only
edit inlines and remove unused var [skip ci]
remove incorrect test
simplify Pow._eval_power
calculate sign(s) - s so full precision is used

Since we are calculating something that should be zero, using
2 digits of precision, with a guarantee that significance is
obtained, is used.
add Examples header to docstring
enumerate cases more clearly in Pow._eval_power
add helper docstrings; use flag to control joining of symbolic exponents
disable joining on the basis of symbolic nonneg base
modify imports and remove XFAIL