compare frozensets as Basic objects

It was wrongly being assumed that if a frozenset was encountered that
it was equal to the other frozen set. This caused arbitrary sorting
of args like Min(1,x) and Min(2,x) since they are both the same function
with a single frozenset argument...but the (1,x) should be less than the
(2,x). So rather than returning 0, the args of the frozenset(s) are
compared.
Redirect standard error to void
Redirect both stdout and stderr to void
Merge pull request #7731 from debugger22/redirect-std-error

Redirect standard error output to void
Merge pull request #7727 from smichr/compare

compare frozensets as Basic objects (re-addresses #958)
Removed wrong inline comment
Merge branch 'master' of https://github.com/sympy/sympy into basicvector