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
Implies(x, x) -> true
8413: Min and Max are floor and ceiling aware

- facilitate changes with reversed property of Relational which
  reverses the direction of the Relational
special-case +/-oo in _Inequality
put Number on rhs when simplifying Relational

This will allow any test to be written as 0 < x or x > 0 since the former
will turn into the latter by Python rules (unless S(0) < x is written).