Add function to grab items from fieldset

[alex-dicko]

Added a small function to BoundFieldset to get items from the fieldsets:

I wanted to add a new field "columns" to a fieldset:

class ThemeConfigForm(BetterModelForm):
    class Meta:
        model = ThemeConfig
        fields = '__all__'
        fieldsets = [
            ('general_information', {
                'legend': 'General Information',
                'columns' 4,
                'fields': [
                    ...
                ]
            }),
        ]

<div class="col-12 col-lg-{% if fieldset.columns %}{{ fieldset.columns }}{% else %}{{ columns }}{% endif   %}">
    ...
</div>

Otherwise you would have to do fieldset.fieldset.columns