Merge remote-tracking branch 'author/master'
Added Windows 8.1 to known OS types (as Windows81, Windows81_64)
Merge pull request #858 from mormegil-cz/add-win81-ostype

Added Windows 8.1 to known OS types (as Windows81, Windows81_64)
Merge remote-tracking branch 'author/master'
Merge remote-tracking branch 'origin/master'