Add support for .zip files

[rladstaetter]

Is your feature request related to a problem? Please describe.

It would be great if LogoRRR would open zip files which contain log files and display them. Like that users wouldn't need to unzip them manually. Much like the feature to drop in directories.

LogoRRR should just open all files it finds in those zip files, ask later if those files are really text files or not. Files which trigger some sort of an exception are just ignored, maybe with a warning.

[rladstaetter]

Added zip file support by handling zip files as containers for log files. Settings are remembered as well for each file.