Resource registries: values for JS/CSS resource don't ignore trailing/leading whitespaces

[zopyx]

The configuration of JS and CSS resources in registry.xml is sensitive to trailing or leading whitespaces

<value key="css">             <element>++resource++xmldirector.plonecore/DataTables/media/css/jquery.dataTables.css</element>  </value>

Having whitespace before or after the path leads to often undetected compilation problems that are not reported properly. Either the error reporting should be improved or the paths should be stripped from whitespaces.

[davisagli]

In Plone 6 css and js are no longer configured in the registry in this way, but I suspect the broader issue still remains and needs some thought about when it is safe to strip registry values and when it isn't.