Centre tables, figures and images

For tables centre the table itself, NOT the text inside.

For figures, images and other type of diagram-ish things centre both the diagram and the (caption) texts.

I did some local hacking and believe it is something like:

.align-default {
	margin-left: auto;
	margin-right: auto;
}

.align-default.image, .align-default.figure {
	text-align: center;
}

Test properly!