Add support for D-pad as POV

[fixfactory]

It would be great to have a configuration option for "D-pad as POV".

What is POV?
It stands for "Point of View Hat" and is the typical way a D-pad is represented in the driver of a game controller. See the screenshots below as an example comparing an Xbox controller to the WUSBMote.

Currently, the adapter has the option "D-pad as axes", which is mapping the D-pad to the X and Y axes. Without the option, each D-pad direction is mapped to a different button. However, in some games, neither of these options are supported. Some games support only a POV. An example is Mortal Kombat Trilogy on GOG.

I'm testing this with Adapter Manager 2.1.28, with a Classic controller to USB adapter V3, on firmware 2.2.7, and connected to a Classic Controller Pro.

Thanks for the great software.