Fix incorrect interval in annotations

[PierreGtch]

The annotations added by SetRawAnnotations do not take into account the case when a dataset’s interval does not start at 0. This PR fixes it.

[PierreGtch]

Datasets affected since version 1.0:

imagery BNCI2014_001	interval=[2, 6]
imagery BNCI2014_002	interval=[3, 8]
imagery BNCI2014_004	interval=[3, 7.5]
imagery BNCI2015_004	interval=[3, 10]
imagery Weibo2014	interval=[3, 7]
p300 Huebner2017	interval=[-0.2, 0.7]
p300 Huebner2018	interval=[-0.2, 0.7]
p300 Sosulski2019	interval=[-0.2, 1]
ssvep Kalunga2016	interval=[2, 4]
ssvep MAMEM1	interval=[1, 4]
ssvep MAMEM2	interval=[1, 4]
ssvep MAMEM3	interval=[1, 4]
ssvep Nakanishi2015	interval=[0.15, 4.3]
ssvep Wang2016	interval=[0.5, 5.5]

[bruAristimunha]

We need to create more tests for this situation, but for a new PR!

[PierreGtch]

A bit more context: In 1.0.0, for all the datasets where interval[0]!=0, the raw.annotations were set to start exactly at the onset events[:,0], and not at events[:,0] + sfreq * interval[0].

The durations in the annotations were correct.

This did not affect the creation of epochs when using MOABB’s paradigms.
However, this affected the codes loading the raw data from MOABB and doing the epoching externally by relying on the annotations and ignoring the dataset’s interval, which is the case in Braindecode.

[sylvchev]

Ok, that why there was no regression in MOABB but it was the case for Braindecode. Good catch.