don't evaluate bool(Relational)
TransformationSet -> ImageSet, transform -> image
TransformationSet -> ImageSet in printing/docs
deprecate TransformationSet
add fields to deprecated flag on TransformationSet
Change feature keyword in TransformationSet deprecation
add imageset
imageset of Intervals that cross 0
Fix issue 3744: simplify nseries output with factor_terms()

    The calculate_series should always return a non-zero
    value for nontrivial expression.  Let's do some cheap
    simplifications to check the result is not zero and
    call nseries() with increased n if it is.
Drop workaround for issue 3744 in limit()
Add._eval_as_leading_term(): check for zero output

    _eval_as_leading_term should always return a non-zero value
    from nontrivial expression.  Lets substract the returned
    expression (equal to zero) from the original one an restart
    _eval_as_leading_term() calculation.  See also issue 3744.
Fix failing test in test_integrals.py
fix import in test_fancysets
add import to imageset docstring
Merge remote-tracking branch 'rlamy/Relational' into relational

Conflicts:
	sympy/core/relational.py
Update the docstring of Relational.
Remove extra sorting step from tests whenever possible.
Test chebyshevt_root and chebyshevu_root with valid arguments.
Always specify the sort key when sorting.
Don't rely on the truth value of Rational.