"Aligned" math environments with arrows for comments
Description
This package provides an environment WithArrows which is
similar to the environment aligned of amsmath (and mathtools),
but gives the possibility to draw arrows on the right side of
the alignment. These arrows are usually used to give
explanations concerning the mathematical calculus presented.
The package requires the following other LaTeX packages: expl3,
footnote, l3keys2e, tikz, and xparse.
