[O] beamer export and links with spaces

[David Belohrad]

Dear All,

i'm using org documents export to beamer. Recently I've changed my directory 
structures for the screenshots such, that they are located under date 
subdirectories, e.g.:

screenshots/22 January 2016/140808_21161vUU.png


If I'm going org-type beamer document, I was always using this type of 
declaration to export the figure:

** Summary from previous session
#+BEGIN_CENTER
#+ATTR_LaTeX: :width 0.8\linewidth
[[file:screenshots/22%20January%202016/140808_21161vUU.png]]
#+END_CENTER

as you can see, the spaces are replaced by %20, which is perfectly fine if 
browsing the file in emacs and clicking on the link. The image is correctly 
opened.

This however does not work when beamer/latex is exported, as the org snippet 
gets translated into:


\section{Summary from previous session}
\label{sec:orgheadline2}
\begin{frame}[label={sec:orgheadline1}]{Summary from previous session}
\begin{center}
\includegraphics[width=0.8\linewidth]{screenshots/22%20January%202016/140808_21161vUU.png}
\end{center}
\end{frame}

hence the includegraphics does not contain space, but contains %20. Such file 
cannot be found.

What is the way to make it working? It seems that includegraphics generally 
does not like spaces inside unless one uses e.g. grffile, so the problem could 
be resolved just by replacing %20 in the latex output by an ordinary space and 
including \usepackage[space]{grffile}.

any hint?

thanks
.d.