Test cases to check - including TC for ISSUE-28

Hi all

As you might know, Alex is the new collaborator for collecting, 
documenting and packaging the Test Cases.
We would like to invite you to check the following R2RML test cases:

    * for the database 2tables1primarykey1foreingkey [1], the test case is

         R2RMLTC0009 [2] : Test that results from distinct parts of the 
mapping can be directed to different target graphs.

    * for the database 2tables2duplicates0nulls [3], the test cases are
      (related to ISSUE-28)

         R2RMLTC0019a [4] : Tests that blank nodes with same identifier 
and in the same graph but generated by different logical rows are 
considered equivalent.

         R2RMLTC0019b [5] : Tests that blank nodes with same identifier 
and in the same graph but generated by via different part of the mapping 
are considered equivalent.

Thank you in advance and regards

Alex/Boris


[1] 
http://www.w3.org/2001/sw/rdb2rdf/wiki/R2RML_Test_Cases_v1#2tables1primarykey1foreingkey
[2] http://www.w3.org/2001/sw/rdb2rdf/wiki/R2RML_Test_Cases_v1#R2RMLTC0009
[3] 
http://www.w3.org/2001/sw/rdb2rdf/wiki/R2RML_Test_Cases_v1#2tables2duplicates0nulls
[4] http://www.w3.org/2001/sw/rdb2rdf/wiki/R2RML_Test_Cases_v1#R2RMLTC0019a
[5] http://www.w3.org/2001/sw/rdb2rdf/wiki/R2RML_Test_Cases_v1#R2RMLTC0019b