2.0.2.0.3 changes

+ Virtual document content class added with template based reporting feature.

2.0.2.0.2 changes

+ No owner roles over Heading objects. Folder owner recieves editor 
  role automatically.

+ Editor can change document's owner

+ Heading view displays editors list

+ From/Till date search options

+ NauSite _can_ work without Tracker product

+ Mail messages templates moved from python code to the NauSite skins 
  and editable through ZMI

- Fixed security issue which allowed users to acces list of all 
  system folders.

- Mail text encoding is explicitly specified.

- External Site presentation bugs fixed.
