Support HDT format

[xdobry]

Such format could be ideal to load bigger rdf data but seems not to have
big support by rdf vendors and rdf tools.

https://www.rdfhdt.org/
science and research project sponsored by spain ministry of Economy.

HDT has rust support and good documentation
https://crates.io/crates/hdt

Used in
https://crates.io/crates/rickview

Probably the copy
https://www.kaggle.com/search?q=hdt+in%3Adatasets

It would be quite easy to support loading data from this format.

Please comment or like it.

In ticket #4 I work on own data persistency using some own binary format.
I want also to store additional information to graph visualization. So store more or less the application state with rdf data as project file.
Probably hdt has another indexing strategy as rdf-glance.
HTD seems index tripples and not consider RDF:type