Cannot link to blank nodes

[berezovskyi]

Lyo allows resources to the serialised as blank nodes if null URI is passed the ctor. There might be a need to link to the still. Turtle and other formats allow to reference blank nodes by their IDs:

However, there is no way to create a Link to a resource instance w/o an about URI that would later be resolved to a blank node reference at the marshalling stage by the JMH. Here is the expected behaviour:

_:f10d8ddad853 a :clear;
      :prop "value" .

:res1 a :resource;
  :clear _:f10d8ddad853 .

Here is the actual behaviour:

[ a :clear;
    :prop "value" ] .

:res1 a :resource .

[berezovskyi]

cc @jadelkhoury @jamsden @yashkhatri