No stacktrace when encountering problems while building a base URL. It's not necessar...

No stacktrace when encountering problems while building a base URL. It's not necessary and draws too much attention. Instead added the URL to the log message that causes the problem.
Don't validate Base URLs anymore in FOUserAgent because that produces errors (because an URL cannot be built) if a symbolic URI is used which is later resolved through a URIResolver.
Improved support for relative URLs for accessing font resources.
ServletContextURIResolver can now use a base URI that starts with "servlet-context:".

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@388766 13f79535-47bb-0310-9956-ffa450edef68