Add stimulus_type metadata table

[oruebel]

The metadata structure for describing stimulus types should be further refined. One proposal for this has been to add a separatestimulus_types stable which in turn should be referenced from the the sweep_sequences (aka, sequential_recording) table. Having the stimulus_types as a separate table would have the added advantage that the table can be reused across experiments.

[EnricoScanta]

Is this feature going to be implemented?
Cheers

[oruebel]

This is not planned for the initial implementation since it will take some more time to determine and standardize the stimulus metadata. For now, I would suggest to use the sequential_recording table to store metadata about the stimulus.