Adds filtering by ranges of dates birth in the admin filter sidebar.

https://github.com/coolchevy/django-rangevaluesfilterspec

Example:

from django.db import models
import rangevaluesfilterspec
 
class Person(models.Model):
    dateofbirth = models.DateField()
    dateofbirth.age_filter_range = [18,21,30,40]

    class Admin:
        list_filter = ['dateofbirth']