Fixed inability to load IFMML documents now that we're packaging the application in a JAR file.  The old code set up a fixed relative path to the DTD in the file system assuming the user's working directory was at the root of the classpath.  Could have simply changed this URL to reference the DTD within the JAR file, but also wanted to remove the dependency on where the application was started from.

Added a public identifier for the IFMML DTD and changed the system identifier to a dummy URL.  Modified the IFMML parsing code to map the public identifier to the DTD embedded in the JAR file.