pretrain.datasets

What a pretraining run reads, shared by the models that fit the same objective.

IBLBrainWideBenchMaskModelingSpikes	Binned spikes alone, for objectives that mask them and reconstruct them.
IBLBrainWideBenchSingleTaskBehavior	Spikes aligned to one behavioral target.
IBLBrainWideBenchMultiTaskBehavior	Spikes aligned to several behavioral targets at once.