feat: added support for version history (cube filter, Cube.in(), improved cube DESCRIBE query)

[bergos]

This PR:

• extends the DESCRIBE query used to get the cube metadata. Now it also checks the inverse of schema:hasPart for the version history.
• adds a Cube.in() method. It's just forwarding the clownface method to be able to check the version history.
• adds a Cube.filter.patternIn() filter. Adds a triple pattern with the cube variable as object.
• adds a Cube.filter.isPartOf() filter. It's an inverse filter of schema:hasPart to filter based on the version history term.
• examples how to find the version history term and how to use it to find the latest version of a specific cube.