Feature Request - Visual mode checkbox toggle?

[garymh]

Is it possible to have a visual mode version of the checkbox toggle mapping? I often have markdown checklists I want to quickly complete and I'd love to be able to :ToggleCheckbox over a range.

[kaymmm]

addressed in #131. I used :'<,'>ToggleCheckboxVisual or <leader>x in visual mode as the ways of calling the new function.