Blechpy

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- Fix error launching spike sorter gui from dataset
- setup to run blech clust using UMAP instead of PCA is desired

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- Change multiprocessing context to spawn to hopefully resolve freezing on many core machines
- Minor edits to spike sorting GUI

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- Fix implment_umap typo in blech_clustering
- Lauching sort_spikes now returns handle to GUI for command-line manipulation
- Can now run spike detection and clustering without multiprocessing

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- Add pre_process_for_clustering to dataset, to run all steps prior to clustering
- Fix error from re-factoring spike_sorting.py
- Fix error in delete unit for renaming unit plots
- Add UMAP visualization and cluster splitting to spike sorting

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- Fix typo in dataset.py

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- Fix spike sorting to re-compute pca after splitting or merging clusters
- Fix held unit analysis to handle multiple matches for single units by
choosing units with lowest J3
* Big Changes:
- Seperate spike detection and spike clustering
- Make objects to handle spike detection, spike clustering, and spike sorting
- Make GUI for spike sorting
- Can now cluster and sort over multiple recordings at once
- Change file structure occurring from clustering