Use non-interactive install when updating with WinSparkle

[rillig]

The auto-update feature of Poedit is already good, but it could be improved in a few details:

• When installing an update, I currently have to accept the license agreement again. As long as the license terms haven't changed between the versions, it should not be necessary to ask again.
• The question whether I want to start Poedit seems redundant to me. I had opened Poedit to do some work, then the update question interrupted me, therefore of course I want to continue working where I left off. Are there use cases where I wouldn't want to restart Poedit after an update?
• When I have a document opened before the update, that document should be opened after the update again. Ideally all the application state should be saved and restored between the versions. This includes the open windows, their position, the currently edited message.

[vslavik]

Related: vslavik/winsparkle#132