Reimplement SPIN API

[namedgraph]

SPIN API 1.4.0 are built with old versions of Jena and contains multiple bugs:
https://groups.google.com/forum/#!msg/topbraid-users/AVXXEJdbQzk/w5NrJFs35-0J

Later versions use AGPL license and are bundled with experimental SHACL API:
https://github.com/TopQuadrant/shacl

It looks like the reasonable thing to do would be to implement the relevant parts of SPIN (constraints and constructors) under Apache License.

[namedgraph]

In 7ff2150 SPIN API upgraded to 2.0.0 which is based on Jena 3.0.1.

[namedgraph]

Not be necessary anymore since SPIN API has recenly become open-source and we have our own fork:
https://github.com/AtomGraph/spinrdf