Render multiselects as checkboxes

[rolandgeider]

How to use the multiselect boxes is not always clear, who knows that it's necessary to do Click + Ctrl? (mobile is in this aspect better because mobile browsers render it differently)

It should be possible to render this as a list of checkboxes that can be selected individually. While django has a CheckboxSelectMultiple that does this, the HTML is incompatible with the bootstrap classes so the result looks really ugly. The problem in this issue is finding a solution for this. There are some django apps to render forms with the bootstrap classes, if they are needed for this to work, that's OK too.