Comment 7 for bug 1451778

I've found a pragmatic solution:
- basically use the absolute path of files and directories
- normalize it by using QDir::cleanPath()
- use the canonical path only for security tokens

This strategy preserves symlinks, while redundant parts of the path are removed. The corresponding static functions will be located in MFile and MDir. All invocations of QDir::absolutePath(), QFileInfo::absolutePath(), and QFileInfo::absoluteFilePath() will be replace by MDir::normalizedPath(), MFile::normalizedPath(), and MFile::normalizedFilePath() respectively.

PR will follow shortly. I've prepared a branch for 1.12, but rebasing it on master would also be possible.