antsApplyTransforms allows -d 4 with a 3D warp field

[cookpa]

As reported in #1717

antsApplyTransforms -d 4 -r fixed.nii.gz -i moving.nii.gz -t antsregsyn_1Warp.nii.gz -o output.nii.gz --verbose

This will run without errors though the output will be wrong.

[cookpa]

Actually I might have fixed this already in #1694, will check

[cookpa]

OK confirmed, it still allows

antsApplyTransforms -d 4 -r fixed.nii.gz -i timeseries.nii.gz -t antsregsyn_1Warp.nii.gz -o output.nii.gz --verbose

where timeseries.nii.gz is 4D, but the warp is only 3D. But it only then outputs the first volume, so it will be obviously wrong.