Issue #311: Assign a Icon to a File Measurement Types (dismine/valentina)

New issue 311: Assign a Icon to a File Measurement Types https://bitbucket.org/valentinateam/valentina/issue/311/assign-a-icon-to-a-file-measurement-types

Roman Telezhinskyi:

I propose assign our custom icon for VST and VIT file formats. All that need it is icon and information about assigning custom icons in Windows, Linux and OSX.