As reported by @cepa995 in #652.

Description
Axis sharing was hard-coded to use columns, but rows are desired for subject with many images (>2):

import torchio as tio
dataset = tio.datasets.RSNAMICCAI('root')
subject = dataset[0]  # it's subject 00792
transform = tio.Compose([
                tio.ToCanonical(),
                tio.Resample("T2w"),
                tio.RescaleIntensity((-1, 1)),
                tio.OneHot(),
            ])
transform(subject).plot()

Before:

After:

Checklist

• I have read the CONTRIBUTING docs and have a developer setup (especially important are pre-commitand pytest)
• Non-breaking change (would not break existing functionality)
• Breaking change (would cause existing functionality to change)
• Tests added or modified to cover the changes
• Integration tests passed locally by running pytest
• In-line docstrings updated
• Documentation updated, tested running make html inside the docs/ folder
• This pull request is ready to be reviewed
• If the PR is ready and there are multiple commits, I have squashed them and force-pushed