Positioning backend for Windows

Using the legacy https://msdn.microsoft.com/en-us/library/windows/desktop/dd317755%28v=vs.85%29.aspx API it should be possible to have a positioning plugin for Windows 7 and up. It might not provide more than position (no satellite and monitoring), but it is a lot better than nothing.

For Windows 8 and up the existing winrt plugin based on https://msdn.microsoft.com/en-us/library/windows/desktop/windows.devices.geolocation.aspx is fine, with a few minor changes (LIBS += -lruntimeobject). It could be renamed to 'windows' at some point. However, Win 10 has new requirements (RequestAccessAsync must be called to pop up the UI confirmation before the PositionChanged events can be requested), it seems, which complicates things.

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Update: After some investigation it turns out the old location API is pretty useless as GPS receivers do not usually come with the necessary drivers that would make them show up as location-capable sensors in Windows, unless one uses something like http://www.turboirc.com/gps7/

Instead, the drivers are typically providing an USB-to-COM translation. Therefore it may be more sensible to have a simple Qt Serial Port-based plugin that reads NMEA sentences from a serial port. This would then work with popular USB receivers like the ones from GlobalSat.