minipages converted to sidebyside

[davidfarmer]

There are many places where the LaTeX source uses minipage, which I convert to sidebyside.

It would be good if some subset of those could be identified and converted to something more structural.
Suggestions welcome.

Note: a side-effect is unknown xref's, since SL2X does not recognize minipage an an environment
that can be given a label.

[davidfarmer]

An example of the label problem is

Label
\label{fig:hzasy}
is in a minipage in the file
01_Limits_Involving_Infinity.tex