Warning/Cleanup of Log-Files

[StefanFranzWeiser]

At the moment Log-Files are written without respect to the available space on the hard disk.
Some type of automatic cleanup task or user warning should be added, so the user knows about the high efford of disk space for log files.

[holzerma]

We decided to take this into account.
PR for this issue are highly welcome, feel free to create a PR.