The \maybebm and \maybeit macros can be used in maths
expressions to make the arguments typeset as bold or italic
respectively if the surrounding context is appropriate. They
are useful for writing user macros for use in general contexts.
\maybebm is especially appropriate when section titles contain
math expressions, since the title will appear bold but the
header and table of contents usually replicate the title in
normal width. It uses the bm package to make things bold
\maybeit performs a similar role to \mathrm{} but the maths
expression will be italicised if the surrounding text is.
\maybeitsubscript is provided to shift subscripts to the left
if the expression is italicised.
