Meggie

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- Make meggie consistent across induced response channel averages: baseline is corrected to before averaging over channels
- Pin matplotlib==3.7.3 as newer matplotlibs are not compatible with pinned mne==1.3.1
- Fix bug where saving TFR's resulted in csv file for each subject even though there should be only one file with all subjects' data in.

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- Fix error that happened when saving TFR without baselining

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- Allow selecting multiple channels for rereferencing

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- Remove a forgotten debug command
- Fix tests

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- Update to mne==1.3.1
- Replace heuristic find_stim_channel with mne's own

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- Better color defaults for TFR's
- Fix regression in group average assertions