Bugfixes:

- #5045: When switching from Content -> Advanced Content lots of PHP errors
- #5056: page_tabs not working for users without permission "Manage All Content"
- #5073: incorrect display of files when opening filepicker
- fixed minor bug where the option "allow_none" of content blocks of type image/file was not shown when template has been edited

Improvements:

- added filemanagement and upload functions to content blocks of type image/file
- added breadcumbs to filepicker
- admins may browse the entire dir tree in filepicker file browser regardless of template params
- added mime type checking to get file type
- added rawurlencode in src attribs to display images with weird filenames.

miscellaneous:

- removed OOP stuff (private/public/protected) to gain more compatibility with PHP4
- changed ajax functions to return xml values
- removed usage of ImageManager once and for all. (caused only trouble)