add evaluate context manager
Extend use of global_evaluate
Add cacheit decorator back onto AssocOp.__new__
cacheit inspects global variables
Extend global_evaluate

Find cases like def foo(..., evaluate=True)
FiniteSet plays well with evalaute=False
fix typo for global_evaluate
small docstring for evaluate context manager
Move powsimp assertion to tests
Merge branch 'master' into with-evaluate

Conflicts:
	sympy/geometry/point.py
docstring for evaluate context manager
Merge branch 'master' into with-evaluate
Merge branch 'with-evaluate' of github.com:mrocklin/sympy into with-evaluate

Conflicts:
	sympy/core/evaluate.py
evaluate=None means trust global, not False

This was assumed in a test.  I'm unassuming it.  Hopefully no one cares
Workaround Dummy's printing in Subs constructor (fixes #7068)
Add test for issue 7068
minor doc fix for pde.py
Have piecewise sanitize boolean arguements
Test cse on sanitized Piecewise
Simplify Not when applied to a Relational.

Replaces the Not object with a corresponding Relational object with equivalent
meaning.