Demo day-one patch

Hi,

A little day-one patch for the demo, here are the changes:

• Cross removes square setting now always removes square - New setting for Square removes Cross added - Fixed a music bug when restarting an already won picross - Win sound (fireworks) is less loud now - Done numbers are more transparent - Hidden picross?

Thank you to everyone who played and enjoyed the demo, and to everyone who gave me your feedbacks it's always appreciated.

Have fun, Edwin.