Plugin styles are not loaded

[lmachucab]

I'm trying to update plugin divalign2 to make it compatible with the s5 renderer plugin. However, the main issue is that s5 does not load plugins' style.css files.

Demo: http://ryan.gulix.cl/tests.doku/dokuwiki-2016-06-26d/doku.php/divalign2?do=export_s5

Expected

• Slides 2, 3 and 4 show aligned text.
• Observing the source code includes a link rel="stylesheet" for the divalign2 plugin.

Observed

• Slides 2, 3 and 4 show no aligned text.
• Observing the source code does not include invocations to the corresponding stylesheet files.

I figure out this affects not only s5 but also any other plugin that does styling.