- Split TeX block into Math and TeX
- in markdown reader, use one or the other depending on type
- in HTML writer (etc.), ignore TeX blocks, print Math blocks verbatim.
- detect .htex output extension; use html writer with --gladtex option
- new options:
  --gladtex -- put math btw tags <EQ> </EQ>
        (put these in directory with name based on html file)
  --mimetex OPT -- <img src="/cgi-bin/mimetex.cgi?f(x)=\int_{-\infty}^xe^{-t^2}dt" alt="" border=0 align=middle>
     OPT specifies path to mimetex.cgi?, defaults to /cgi-bin/mimetex.cgi
- document this