Mark statement inputs in the block representation; update `getInputs` and `getSubstack` about scratch-vm HOT 2 CLOSED

Also related to #74 (should probably wait until we resolve that).

from scratch-vm.

Hmmm... it seems like it might be impossible to reconstruct this data (e.g., an isBranch boolean) from what Blockly gives us. If the statement input is created during a CREATE event, it's easy (since the XML includes whether it's a statement or value input). But, if a block is moved into a statement input during editing, we can't tell if it's a value input or a statement input. Because the original CREATE XML only includes the input if it's filled (e.g., no empty statement input), whether it's a value or statement input is completely lost.

Either we change the Blockly MOVE event to include info about what kind of input it's being moved into, we change the CREATE event to include empty statement inputs, or we stick with using a prefix for substacks/branches.

from scratch-vm.