Add support for embedding without server

[btiernay]

It would be nice to be able to use embed r43ples as library instead of using it as a standalone process. This might be useful to add-on to various LDPs based Jena / Sesame (e.g. Marmotta). For example, such is possible with ShExcala or the SPIN API.

[markusgraube]

This is in fact a good idea. I will produce a library without binary and without dependencies.

However, I am not quite sure where to place to abstraction layer best. I will give a try in the next weeks.