Feature reporting
This is based on the conversation in:
https://github.com/mintty/mintty/issues/881
And further development in these documents:
https://docs.google.com/spreadsheets/d/1H4OK8z98ptySnAPjlej56lrL6b0S1j6okwp7KLRTDBQ/edit#gid=0 https://docs.google.com/document/d/1Is0xKlJTyhuPBVypzJHgNtKsZkStoI2WTLfiVSp6RC4/edit