Add dioptre in physics.units
Add support for evaluate kwarg in relational classes

(Plus some pep8 fixes for sympy/core/tests/test_relational.py)
Redirect stdout and stderr to void when git push fails [skip ci]
Make build_doc run only for the first job
Compare only with the integral part after the period
Merge pull request #7782 from debugger22/dioptre-unit

Add dioptre in physics.units
Merge pull request #7787 from debugger22/build_doc

Make build_doc run only for the first job and redirect stdout and stderr to void when git push fails.
Update finite_diff.py

Fixed typos.
build_doc: fix a syntax error

This was introduced in #7787.
Merge pull request #7795 from certik/travis_fix

build_doc: fix a syntax error
Merge pull request #7778 from skirpichev/evaluate-kwarg-for-rel

Add support for evaluate kwarg in relational classes
Merge pull request #7794 from naslundx/patch-1

Update finite_diff.py
Add Marcus Näslund to AUTHORS/aboutus. Welcome to SymPy
Implement rewrite as Sum helper for the Product
Implement numerical evaluation of products (closes #7651)
Add check for finite limits in evalf_prod: use doit() for this case
Use evalf_sum to evaluate Sum after rewritting the Product

In case evalf_sum can't do the Sum - it should raise NotImplementedError.
Then, evalf can return the original expr for the Product.
Add missing import
Revert last two commits