Don't use new assumptions in the sets module
Implement a symbolic object for the relation "is an element of"

1. fixes #6194
2. contains methods of set classes were modified to return
   BooleanAtom's, not True/False
Printing support for Contains class
Fix some asserts to check if foo.contains(bar) is S.true
Remove .is_infinitesimal assumption
Merge pull request #7989 from skirpichev/contains

Implement a symbolic object for the relation "is an element of"
Merge pull request #7995 from skirpichev/remove-is_infinitesimal

Remove .is_infinitesimal assumption
Refactor processing of inequalities with oo [1/9]

fixes #7775
Refactor processing of inequalities with oo [2/9]

If we don't know the boundedness: _eval_is_positive/negative should
return None.

fixes #7798
fixes #7841
Refactor processing of inequalities with oo [3/9]

fix tests in test_sets.py
Refactor processing of inequalities with oo [4/9]

fix wester's tests
Refactor processing of inequalities with oo [5/9]

fix tests for inequalities.py
Refactor processing of inequalities with oo [6/9]

More tests fixed
Refactor processing of inequalities with oo [7/9]

Add import for oo
Refactor processing of inequalities with oo [8/9]

Fixes for physics/quantum
Refactor processing of inequalities with oo [9/9]

Fix doctests in delta.py
Deprecate set.is_real property, use set.is_subset(Reals) instead

fixes #6212