Define mimetype (application/x-cantor) for cantor worksheets (.cws)
At least on my system, I have to manually create a file type for 'cantor worksheet' (.cws) files to set Cantor as the default application for them. Otherwise, Dolphin just detects it as a zip archive and opens it with Ark. This pull request adds an xml file that is copied to
/usr/share/mime/packages/ so that a mimetype
application/x-cantor is defined systemwide for cantor worksheets.