FIX #2352 - open file using ASCII-US encoding

[robertoostenveld]

@schoffelen I wonder whether we should do this more explicitly for other file formats as well. We don't encounter this problem very often, but this certainly not the first time.

At other places in the code we do it explicitly when reading, for example

char(fread(fid, 16, 'uint8=>char'))

I think that any piece of code that freads a char without explicit specification of the character encoding is at risk.

[github-actions]

You should test whether your modifications do not break anything.
See https://www.fieldtriptoolbox.org/development/testing/

When inside the DCCN, please also consider testing: test_nicolet_reading