Provide \Oldincludegraphics in beamer like in LaTeX

In the old solution there was no way to use a LaTeX image where only the
height was used to scale the image -- the width was always implicitly
set as well leading to wrong aspect ratios.

Provide a command \Oldincludegraphics which does just what
\includegraphics would do in the LaTeX template. That we the same input
markup could be used for beamer and LaTeX templates.

default.beamer

@@ -62,7 +62,8 @@ $if(graphics)$
   \fi
 }
 \makeatother
-\setkeys{Gin}{width=\ScaleIfNeeded}
+\let\Oldincludegraphics\includegraphics
+\renewcommand{\includegraphics}[2][]{\Oldincludegraphics[width=\ScaleIfNeeded]{#2}}
 $endif$
 
 % Comment these out if you don't want a slide with just the