pretty big commit, sorry for that. Here is a summary of the changes:
* creation of subpackages: binder, diesel, syntax
* the binders are now divided into ToX and FromX traits
* the common binders are now available without any import, and also follow the new organization ToX/FromX
* diesel is now really about constructing and exploring rdf graphs, nothing else
* all syntax stuff is removed from RDFOps and made available udner org.w3.banana.syntax