make the categorybadge model support hierachical badges
add edit form for hierachical category badges
hierachical badges helper
add hierachical category badges to the proposal edit form
allow facet search with hierachical badges
make hierachical facet search work with multiple parents
fix hierachical facets have wrong order
facet search: do not show badges with visible==False
added css classes to customize the facet listing
Add jquery.select-hierarchy library

Modified version of jquery.select-hierarchy, which allows to dynamically
create multiple select widgets out of one select widget with
hierarchical options.

See https://github.com/nidico/jquery-select-hierarchy
Remove default select_child_description
Fix non-global hierarchical categories
Multi-level hierarchical category chooser

If there are hierarchical categories, the hierarchy breadcrumbs are
represented as the description text in the category select options.

This breadcrumb view is used by the modified version of jquery.select-
hierarchy to dynamically create multiple select widgets if javascript is
enabled.

If there's exactly one toplevel category and there are lower level
categories, only these are shown in the toplevel category chooser, and
the (single) toplevel select description is used as the toplevel select
prompt.
Also fix non-global hierarchical categories for edit form

Addendum to d4f21719d44622cf21ab954a11acc40fe01a1540
Fix: Facet search is not working with multiple root items
Implement util function split_filter

Splits a sequence in two lists based on a condition
Use split_filter (better performance)
Avoid trailing '?' after facet reset
Better wording for facet removal ("reset" instead of "remove")
Don't display count for disabled facet items