Patch for ignoring Pre/Post and Interface Extensions within an xsdconfig

I use the Extension Interfaces feature, per http://wiki.apache.org/xmlbeans/ExtensionInterfacesFeature. One of the not so great aspects of this approach is that you currently need to have two individual .xsdconfig files for your project – one that has JUST the namespace info and one that has both namespace AND extension info. To simplify this, I have created a patch for SchemaCompiler and the XMLBean task (tested on 2.1 and 2.2) that adds a new parameter ("noExt") which causes the compiler to filter out any extensions if the flag is set. The end result is that you can use a single .xsdconfig file and just set the flag for the first compilation/generation pass so that interfaces declarations are ignored.