Improve the design somewhat
Prevent creation of sub-folders in the media folder for now

- Remove the Create folder button in the file-browser
- Import and export and properties of an LO can't handle sub-folders of
  media
Implement the possibillity to deprecate parameters in the XWD files

- (optional) parameters can take the attribute deprecated="Reason to
  deprecate"
- Pages can take the attribute deprecated="Reason to deprecate"
- Can mark attributes as flash engine only by adding attribute
  flashonly="true"
- Optional parameters can have attribute tooltip="Explanation of optional
  parameter"