Hi All,

I anticipate that this change may be somewhat contentions because ox-md
explicitly follows only the original Markdown spec from 2003, however
I've thought this over and come to the conclusion that this change is
still in keeping with that, and beneficial.

Currently ox-md simply inherits the output from ox-html's handling of
LaTeX snippets. Needless to say, the original Markdown specification
does not mention LaTeX snippets. As such, by subtly tweaking the output
(either adding $$ or substituting out LaTeX-style \(\) / \[\] for $ /
$$) we are not deviating from the original specification any more than we
already are.

While I don't see any issue with this, I do see some benefits. Namely
that, of the many Markdown variants that now exist, many support LaTeX
snippets, but exclusively in the TeX $$ form. Hence, by applying this
change the overall utility of ox-md is increased.

Let me know what you think,

Timothy