pydrake doc: Use constexpr auto& for nesting aliases

[EricCousineau-TRI]

Resolves #9600

\cc @m-chaturvedi

---

This change is 

[EricCousineau-TRI]

@drake-jenkins-bot mac-highsierra-clang-bazel-experimental please.

[EricCousineau-TRI]

+@jamiesnape for review, please.

Reviewable status: all discussions resolved, platform LGTM missing

[jamiesnape]

Can you unwind the workarounds here?

drake/bindings/pydrake/multibody/rigid_body_tree_py.cc

Lines 261 to 414 in d3c9db3

	auto add_rigid_body_tree_typed_methods = [m, &tree_cls](auto dummy) {
	// N.B. The header files use `Scalar` as the scalar-type template
	// parameter, but `T` is used here for brevity.
	using T = decltype(dummy);
	// Type (a) methods:
	tree_cls
	.def("massMatrix", &RigidBodyTree<double>::massMatrix<T>,
	pydrake_doc.RigidBodyTree.massMatrix.doc)
	.def("centerOfMass", &RigidBodyTree<double>::centerOfMass<T>,
	py::arg("cache"),
	py::arg("model_instance_id_set") =
	RigidBodyTreeConstants::default_model_instance_id_set,
	pydrake_doc.RigidBodyTree.centerOfMass.doc)
	.def("transformVelocityToQDot", [](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache,
	const VectorX<T>& v) {
	return tree.transformVelocityToQDot(cache, v);
	},
	pydrake_doc.RigidBodyTree.transformVelocityToQDot.doc)
	.def("transformQDotToVelocity", [](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache,
	const VectorX<T>& qdot) {
	return tree.transformQDotToVelocity(cache, qdot);
	},
	pydrake_doc.RigidBodyTree.transformQDotToVelocity.doc)
	.def("GetVelocityToQDotMapping", [](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache) {
	return tree.GetVelocityToQDotMapping(cache);
	},
	pydrake_doc.RigidBodyTree.GetVelocityToQDotMapping.doc)
	.def("GetQDotToVelocityMapping", [](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache) {
	return tree.GetQDotToVelocityMapping(cache);
	},
	pydrake_doc.RigidBodyTree.GetQDotToVelocityMapping.doc)
	.def("dynamicsBiasTerm", &RigidBodyTree<double>::dynamicsBiasTerm<T>,
	py::arg("cache"), py::arg("external_wrenches"),
	py::arg("include_velocity_terms") = true,
	pydrake_doc.RigidBodyTree.dynamicsBiasTerm.doc)
	.def("geometricJacobian",
	[](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache, int base_body_or_frame_ind,
	int end_effector_body_or_frame_ind,
	int expressed_in_body_or_frame_ind, bool in_terms_of_qdot) {
	std::vector<int> v_indices;
	auto J = tree.geometricJacobian(
	cache, base_body_or_frame_ind, end_effector_body_or_frame_ind,
	expressed_in_body_or_frame_ind, in_terms_of_qdot, &v_indices);
	return py::make_tuple(J, v_indices);
	},
	py::arg("cache"), py::arg("base_body_or_frame_ind"),
	py::arg("end_effector_body_or_frame_ind"),
	py::arg("expressed_in_body_or_frame_ind"),
	py::arg("in_terms_of_qdot") = false,
	pydrake_doc.RigidBodyTree.geometricJacobian.doc)
	.def("relativeTransform", [](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache,
	int base_or_frame_ind,
	int body_or_frame_ind) {
	return tree.relativeTransform(cache, base_or_frame_ind,
	body_or_frame_ind).matrix();
	},
	py::arg("cache"),
	py::arg("base_or_frame_ind"), py::arg("body_or_frame_ind"),
	pydrake_doc.RigidBodyTree.relativeTransform.doc)
	.def("centerOfMassJacobian",
	&RigidBodyTree<double>::centerOfMassJacobian<T>,
	py::arg("cache"),
	py::arg("model_instance_id_set") =
	RigidBodyTreeConstants::default_model_instance_id_set,
	py::arg("in_terms_of_qdot") = false,
	pydrake_doc.RigidBodyTree.centerOfMassJacobian.doc)
	// centroidalMomentumMatrix
	// forwardKinPositionGradient
	.def("geometricJacobianDotTimesV",
	&RigidBodyTree<double>::geometricJacobianDotTimesV<T>,
	py::arg("cache"),
	py::arg("base_body_or_frame_ind"),
	py::arg("end_effector_body_or_frame_ind"),
	py::arg("expressed_in_body_or_frame_ind"),
	pydrake_doc.RigidBodyTree.geometricJacobianDotTimesV.doc)
	.def("centerOfMassJacobianDotTimesV",
	&RigidBodyTree<double>::centerOfMassJacobianDotTimesV<T>,
	py::arg("cache"),
	py::arg("model_instance_id_set") =
	RigidBodyTreeConstants::default_model_instance_id_set,
	pydrake_doc.RigidBodyTree.centerOfMassJacobianDotTimesV.doc)
	// centroidalMomentumMatrixDotTimesV
	.def("positionConstraints",
	&RigidBodyTree<double>::positionConstraints<T>,
	py::arg("cache"),
	pydrake_doc.RigidBodyTree.positionConstraints.doc)
	.def("positionConstraintsJacobian",
	&RigidBodyTree<double>::positionConstraintsJacobian<T>,
	py::arg("cache"),
	py::arg("in_terms_of_qdot") = true,
	pydrake_doc.RigidBodyTree.positionConstraintsJacobian.doc)
	.def("positionConstraintsJacDotTimesV",
	&RigidBodyTree<double>::positionConstraintsJacDotTimesV<T>,
	py::arg("cache"),
	pydrake_doc.RigidBodyTree.positionConstraintsJacDotTimesV.doc)
	// jointLimitConstriants
	.def("relativeTwist",
	&RigidBodyTree<double>::relativeTwist<T>,
	py::arg("cache"),
	py::arg("base_or_frame_ind"),
	py::arg("body_or_frame_ind"),
	py::arg("expressed_in_body_or_frame_ind"),
	pydrake_doc.RigidBodyTree.relativeTwist.doc)
	// worldMomentumMatrix
	// worldMomentumMatrixDotTimesV
	// transformSpatialAcceleration
	.def("frictionTorques",
	[](const RigidBodyTree<double>* self, const VectorX<T>& v) {
	return self->frictionTorques(v);
	},
	pydrake_doc.RigidBodyTree.frictionTorques.doc)
	.def("inverseDynamics", &RigidBodyTree<double>::inverseDynamics<T>,
	py::arg("cache"),
	py::arg("external_wrenches"),
	py::arg("vd"),
	py::arg("include_velocity_terms") = true,
	pydrake_doc.RigidBodyTree.inverseDynamics.doc)
	// resolveCenterOfPressure
	.def("transformVelocityMappingToQDotMapping",
	[](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache,
	const MatrixX<T>& Av) {
	return tree.transformVelocityMappingToQDotMapping(cache, Av);
	},
	pydrake_doc.RigidBodyTree.transformVelocityMappingToQDotMapping.doc)
	.def("transformQDotMappingToVelocityMapping",
	[](const RigidBodyTree<double>& tree,
	const KinematicsCache<T>& cache,
	const MatrixX<T>& Ap) {
	return tree.transformQDotMappingToVelocityMapping(cache, Ap);
	},
	pydrake_doc.RigidBodyTree.transformQDotMappingToVelocityMapping.doc)
	// relativeQuaternionJacobian
	// relativeRollPitchYawJacobian
	// relativeRollPitchYawJacobianDotTimesV
	// relativeQuaternionJacobianDotTimesV
	// CheckCacheValidity
	.def("doKinematics", [](const RigidBodyTree<double>& tree,
	const VectorX<T>& q) {
	return tree.doKinematics(q);
	},
	pydrake_doc.RigidBodyTree.doKinematics.doc)
	.def("doKinematics", [](const RigidBodyTree<double>& tree,
	const VectorX<T>& q,
	const VectorX<T>& v) {
	return tree.doKinematics(q, v);
	},
	pydrake_doc.RigidBodyTree.doKinematics.doc_2);

[EricCousineau-TRI]

Done.

[jamiesnape]

Reviewed 36 of 36 files at r1.
Reviewable status: all discussions resolved, platform LGTM missing

[jamiesnape]

+@jwnimmer-tri for platform review.

[jwnimmer-tri]

platform.

Reviewed 36 of 36 files at r1.
Reviewable status: complete! all discussions resolved, platform LGTM from [jwnimmer-tri]