Set an automatic module name in the Jar MANIFEST

When this project is used in JPMS modular builds, it causes either warnings or errors because it is not declaring a module name. One possibility would be to declare an automatic module name (full modularization could be done later), see the following blog post for context:

http://branchandbound.net/blog/java/2017/12/automatic-module-name/

It is simple to add the automatic module name configuration to the Maven pom.xml and I can provide a pull request if you are interested. The module name could be org.apache.xmlgraphics.commons.