pandoc-2.0.4: test/command/3450.md

```
% pandoc -fmarkdown-implicit_figures
![image](lalune.jpg){height=2em}
^D
<p><img src="lalune.jpg" alt="image" style="height:2em" /></p>
```
```
% pandoc -fmarkdown-implicit_figures -t latex
![image](lalune.jpg){height=2em}
^D
\includegraphics[width=\textwidth,height=2em]{lalune.jpg}
```