Single turn dataset

[MarcCote]

This PR addresses a number of issues with the new SingleTurnIGLUDataset.

• Add the appropriate block mapping used during the data collection with VoxelWorld_freeze.js.
• Use a stricter definition of what single-turn data point to keep.
  • Only look at games for which a human judged the instructions to be clear enough (i.e. CQ-* with no clarifying question).
  • If clear enough, human was asked to follow the instructions to rebuild the original target structure. Make that structure matches the one from the original game (i.e, for a CQ-game-001 look at game-001)).
  • Initial grid != target grid