[webui] redo this whole 'package links to' thing
[api] do not touch all unchanged projects if updating maintenance list
[webui] finish test case for add_maintained_project
[webui] Get a grip on the theming

* XML views are in app/views
* HTML views are in app/views/webui and app/assets/*/webui/application*
* HTML themes are in app/views/webui/theme/$name and app/assets/*/webui/$name*
* Added the 'bratwurst' theme, successor of 'bento'