integrals: An amendment to spde()

The iterative version of spde() currently assumes that the
coefficient  a  of  Dp  were invariant in the loop, in which
case the values of the multiplier  alpha  are powers of  a.
Otherwise the offset  beta  of the solution will be incorrect.

I have added two test cases where  a  is not invariant.
In the general case,  alpha  can be used instead of a power of  a
to construct the correct value of  beta.
Fix the flickering problem
Add rational kwarg for Mul.as_coeff_mul, like for as_coeff_Mul
Temporarily comment out deploying docs (fixes #8387)
Merge pull request #8428 from skirpichev/8387-fix

Temporarily comment out deploying docs (fixes #8387)
Solved equality of arguments issue in integral.transform fix issue #8400
adjust whitespace
Add Sunny Aggarwal to AUTHORS/aboutus. Welcome to SymPy!
Merge pull request #8448 from sunny94/iss8400_transform

Solved equality of arguments issue in integral.transform fix issue #8400
Merge pull request #8376 from certik/issue3971

Fix the flickering problem
Fix evaluation of reciprocal trigonometric functions in even quadrants

fixes #8421
Merge pull request #8422 from skirpichev/8421-fix

Fix evaluation of reciprocal trigonometric functions in even quadrants
Improve evaluation of relationals with -oo if "other" arg is positive

fixes #8449
Merge pull request #8460 from skirpichev/8449-fix

Improve evaluation of relationals with -oo if "other" arg is nonnegative
Relational.canonical simplifies Ge -> Le and Gt -> Lt

This is made part of Relational simplification.

The presence of Relationals in Booleans sent to equals
raises an error since that routine is not set up to handle
them.
And and Or are complementary-arg aware

In addition, trivially equivalent forms like x > 1 and 1 < x are
recognized.
Implies is complementary-arg aware
Xor is complementary-arg aware
Equivalent is complementary-arg aware
8413: Min and Max are floor and ceiling aware

- facilitate changes with reversed property of Relational which
  reverses the direction of the Relational