[FR] Add Alternate Checkbox: `<`

[mvriel]

Is your feature request related to a problem? Please describe.

For Bullet Journaling, a common mark is to use the < chevron to indicate a task is migrated to the Weekly or Monthly spread. This is present in Minimal and when I switched from Minimal to ITS, my previous (and future) checkboxes 'broke' because they now show as completed.

Describe the solution you'd like

Is it possible to add a new Alternate Checkbox <? I would love for it to be an icon of an arrow pointing backwards (similar to >); though I understand this may be different from the presentation in Minimal. For Bullet Journaling this would be nice.

[SlRvb]

If you update my theme to v1.2.61 < should now be added! Thanks for the suggestion.

[mvriel]

Works like a charm! Thank you!