Use just the first word from #2 to determine language in \markdownRendererInputFencedCodePrototype

[Witiko]

CommonMark specifies that only the first word of a fenced code infostring is typically used to determine language. However, in the definition of \markdownRendererInputFencedCodePrototype for LaTeX and ConTeXt, we use the entire infostring to determine language:

markdown/markdown.dtx

Lines 26290 to 26322 in 6d2b8d6

	inputFencedCode = {%
	\ifx\relax#2\relax
	\VerbatimInput{#1}%
	\else
	\@ifundefined{minted@code}{%
	\@ifundefined{lst@version}{%
	\markdownRendererInputFencedCode{#1}{}%
	% \end{macrocode}
	% \par
	% \begin{markdown}
	%
	% When the \pkg{listings} package is loaded, use it for syntax highlighting.
	%
	% \end{markdown}
	% \begin{macrocode}
	}{%
	\lstinputlisting[language=#2]{#1}%
	}%
	% \end{macrocode}
	% \par
	% \begin{markdown}
	%
	% When the \pkg{minted} package is loaded, use it for syntax highlighting.
	% The \pkg{minted} package is preferred over \pkg{listings}.
	%
	% \end{markdown}
	% \begin{macrocode}
	}{%
	\catcode`\#=6\relax
	\inputminted{#2}{#1}%
	\catcode`\#=12\relax
	}%
	\fi},

markdown/markdown.dtx

Lines 27164 to 27195 in 6d2b8d6

	\def\markdownRendererInputFencedCodePrototype#1#2{%
	\ifx\relax#2\relax
	\typefile{#1}%
	\else
	% \end{macrocode}
	% \par
	% \begin{markdown}
	%
	% The code fence infostring is used as a name from the \Hologo{ConTeXt}
	% \mref{definetyping} macro. This allows the user to set up code highlighting
	% mapping as follows:
	% ````` tex
	% % Map the `TEX` syntax highlighter to the `latex` infostring.
	% \definetyping [latex]
	% \setuptyping [latex] [option=TEX]
	%
	% \starttext
	% \startmarkdown
	% ~~~ latex
	% \documentclass{article}
	% \begin{document}
	% Hello world!
	% \end{document}
	% ~~~
	% \stopmarkdown
	% \stoptext
	% `````````
	%
	% \end{markdown}
	% \begin{macrocode}
	\typefile[#2][]{#1}%
	\fi}%