Remove execute permissions for clipper source files.
Merge pull request #1976 from sapir/clipperperms

Remove execute permissions for clipper source files.
Add message about directories as parameters for --output.
Merge pull request #1979 from sapir/output-dir-msg

Add message about directories as parameters for --output.
Add dir --output msg to README, too.
Merge pull request #1980 from sapir/output-dir-msg

Add dir --output msg to README, too.
Merge branch 'master' of git://github.com/alexrj/slic3r into feature-xs-types
Last cosmetic touch