support negative times for CTF files

So I didn't know this but it seems like CTF has the ability to start its recordings with negative times by using a sync trigger and asking the scanner to include a baseline period.

Other packages Brainstorm (and presumably fieldtrip) respect this field and adjust their time arrays accordingly.

MNE reads in the required field
https://github.com/mne-tools/mne-python/blob/855edbf48835bcee80e773eb7047d0a4caa14a1c/mne/io/ctf/res4.py#L126

and adjusts annotations and bad_segments to account for it.
https://github.com/mne-tools/mne-python/blob/855edbf48835bcee80e773eb7047d0a4caa14a1c/mne/io/ctf/ctf.py#L147-L156

That MNE shifts other stuff and not the time array leads me to believe that MNE can't have negative time values in raw objects. Is that true?

This cropped up because I was doing some custom event marking for an experiment using mne and the resulting events were read into brainstorm and were all shifted by 1 second. In this particular case, I'm time shifting the events before I save them out, solving my immediate issue but it still seems a bit like a bug?

-Luke

Bắt đầu với việc xử lý trường CTF trong mne/io/ctf/res4.py tại vị trí được liên kết, sau đó kiểm tra các điều chỉnh đối với annotation và bad_segments trong mne/io/ctf/ctf.py. Theo dõi cách khoảng thời gian baseline ảnh hưởng đến các giá trị thời gian của dữ liệu raw và việc căn chỉnh sự kiện. Hoàn thành khi các bản ghi CTF có thời gian bắt đầu âm vẫn duy trì được các mảng thời gian, annotation, bad_segments và sự kiện nhất quán.