Release of 1.9.3.

Bugfixes
- Changes in file system:
-- New copy algorithm (maybe not better, but a new one)
-- No double files per folder
-- No double folders per folder
- User cannot create new dir containing "/"
- Removed workaround which displayed 1 Byte instead of 0 Byte in the
user information
- Fixed a bug which caused that the globals where not applied

Feature additions
- First part of xss protection
- Added support for renaming files (directories will follow)

The rating of this build is still "unstable". Use with caution!