Shorten instance search box

This makes sure 5 instance navigation elements fit without wrapping.
category: fix unicode error
category: remove wrong breadcrumbs
fix allow to set proposal category in query on new
Merge branch 'develop' of github.com:liqd/adhocracy into develop
add new proposal button on category page
i18n
change color of tile button
rm buggy absolute positioning of tile button
add formatting help to category long_description
Prevent strange chromium ellipsis bug

see #691
use id instead of title for category image urls

This fixes issues with unicode, spaces and underscores.
rm broken breadcrumbs
add breadcrumbs for categories
better instance settings breadcrumbs
better user settings breadcrumbs
user profile/dashboard breadcrumbs
Fix breadcrumbs wording
don't memoize user breadcrumb entities

the result depends on the state of c.instance
fix breadcrumbs members url