Adds CorePrinting, NSEvent.DoubleClickInterval, removes disfunctional SystemDoubleClickIntervalInTicks

- New module CorePrinting with functions to get and set the default printer.
- Adds DoubleClickInterval function to NSEvent.
- Removes SystemExtensions.SystemDoubleClickIntervalInTicks function because it did not do what it said, and fixing it could lead to undetected issues with existing code.