Make CIF simulator etc fail on CSS (parsing) errors

I've figured out a way to have the CIF simulator fail on CSS (parsing) issues in SVG file. It would then print something like this:

ERROR: SVG image rendering failed for file "main.svg".
CAUSE: CSS problem.
CAUSE: Parsing failed at "-".
CAUSE: (CSSParseException) Identifier expected.

It doesn't give a whole lot of context, as that is not made available in the exception messages provided by Batik's CSS parser. But still, something is better than nothing.

For SVG errors, we already make the simulator fail. We could thus do the same for CSS problems.

In #886 (closed), we've realized that -inkscape-font-specification can't be parsed by Batik. It occurs often in our repo, in examples, test models, etc. Therefore I don't think we should add this error reporting until Batik is fixed and we've adopted this fixed version, in #886 (closed).