Fix post-processing of LaTeX if an image has a forced size

Fix LaTeX post-process if \includegraphics has any option in the
input.  For now, simply ignore such options completely.

rst2latex.sed

@@ -12,4 +12,5 @@
 
 # center images and reduce them to something moderated fitting the page
 # also force an empty line before: fixes placement after \paragraph and with previous text
-s/(.*\\includegraphics)(.*)/\\begin{center}\\begin{minipage}[c]{\\linewidth}\\begin{center}\1[width=\\textwidth,height=0.25\\textheight,keepaspectratio=true]\2\\end{center}\\end{minipage}\\end{center}/
+# we ignore any option the input may have for \includegraphics
+s/(.*\\includegraphics)(\[.*\])?(.*)/\\begin{center}\\begin{minipage}[c]{\\linewidth}\\begin{center}\1[width=\\textwidth,height=0.25\\textheight,keepaspectratio=true]\3\\end{center}\\end{minipage}\\end{center}/