Error parsing SVG sprites

[peuter]

An SVG sprite is a container for multiple SVG-Images. The difference is, that the root svg element has no dimension attributes (width, height, viewBox) buts its symbol children. The compilers images loades throws a warning because it is not able to determine the SVG size.

Example SVG sprite:

<svg xmlns="http://www.w3.org/2000/svg">
	<symbol id="house" viewBox="0 0 96 96">
		<path d="M40,13 L1,48 H12 V80 H32 V56 H48 V80 H68 V48 H79z"/>
	</symbol>
</svg>

This is the related ticket to #690