Removed iterationtools.iterate_topmost_tie_chains_and_components_in_expr().

Use iterate(expr).by_topmost_tie_chains_and_components() instead.
Removed iterationtools.iterate_components_and_grace_containers_in_expr().

Use iterate(expr).by_components_and_grace_containers() instead.
Merged master.
Adjusted IterationAgent docstrings.