Add an option to control whether the classification task is multi label classification or single label classification.

[chuzhixing]

Thank you to the author for opening up this great software. I have a question in the image classification task.

The definition of concepts.

Multi label classification is a classification problem where each sample can be assigned to one or more categories within multiple categories.
Unlike traditional single label classification problems, single label classification assumes that each sample belongs to only one category.

Problem description

I use labelme 5.3.1, which defaults to multi label classification in classification tasks. I checked the issues in the warehouse and there was no discussion on controlling the options for multiple labels and single labels. I want to know,
1 Does labelme support single label classification for classification tasks?
2 If supported, how to set it up in the software?