Attributes not escaped (notably title attribute)

The attributes for the markup that are inserted by the DOM/parser library are not escaped. This causes issues with other plugins like the wp-typography plugin.
Notably $title from get_the_title() can contain markup.
The markup is used unescaped (and the DOM/parser libraries don’t seem to escape either), resulting in broken gallery markup.

https://plugins.trac.www.ads-software.com/browser/gallery-custom-links/trunk/mgcl_linker.php#L13

All values to be used for attributes must be escaped, e.g.

$potentialLinkNode->{'title'} = esc_attr( $title );
[...]
$potentialLinkNode->attr(  'title', esc_attr( $title )  );
[...]
[...] no-lightbox" title="' . esc_attr( $title ) . '" [...]

And for ensuring that the title contains the pure text, use <code>wp_strip_all_tags</code> on the title, e.g.
<pre><code>

$title = wp_strip_all_tags( get_the_title( $mediaId ) );

`
Newlines are in title attribute value should be allowed and supported now, hence the second argument for wp_strip_all_tags to also strip the newlines staid the default (false)-