#318 Allow candidates to add links to their profile

The extra fields in the edit_profile form are displayed if the user is a
candidate. When the form is saved, the links are added to the candidate
using the generic foreign key in the Link model.
Move link fields to the end of edit_profile form
Show candidate links in public profile
Fix icon paths and add missing icons

Also use object_links to display them, and move them to be below the
candidate picture and description.
Use icons from Open Knesset rather than different ones
fix icons
prevent problems in profile page when is_candidate has 0 or 2 lists