Adds support for divs

[GuillaumeAllain]

Will print the name and the caption if present on the same line.

This adds cmp completion for these cases from pandoc-crossref

<div id="fig:figureRef" class="subfigures">

![a](image1.png){#fig:figureRefA}

![b](image2.png){#fig:figureRefB}

Figure 1: Caption of figure. a — subfigure 1 caption, b — subfigure 2
caption

</div>

::::: {#fig:figureComp}
![a](image1.png){#fig:figureCompA}
![b](image2.png){#fig:figureCompB}

Caption
:::::


\`\`\`{#lst:code .haskell caption="Listing caption"}
main :: IO ()
main = putStrLn "Hello World!"
\`\`\`

This PR also catches an error when value is empty inside vim.trim. It used to happened with these fenced divs for example. If not in this list of divs, no error will be raised but no cmp suggestion as well.

[aspeddro]

Sorry for the delay, I'm leaving some comments before merging.