Barfi

- Add Block state to store data private to the block. Using block.get_state('key'), block.set_state('key').
- Block state also stores execution status and errors. Using block.get_state('info'), block.set_state('info'). Note: 'info' is a reserved key.
- When a block fails on its compute function, its descendants are skipped and the rest of the blocks are computed.
- Add delete schema function. (zabrewer)

- Fix base_blocks_list passed to the compute engine.

- Add option to categories the Blocks with a category in a sub-menu in the context menu on right-click>add-node.

- Add Block option.
- Add tests for Block option and update tests for interfaces.
- Add get, set for option to be used inside compute_engine and update compute_engine to handle option value from frontend

- Change barfo.Block method references from `calculate` to `compute`

- Change the frontend BlockEditor.vue to make use of listeners to make the unique names of the Blocks.