Convert from Silverlight App to UWA

[Apfelkuchen91]

To support new platforms and VS2017 it would be nice if the projects are converted to UWA.

[BMurri]

Would be nice. However, on at least one ad platform, in the past year the ratio of Win81 vs Win10 in the mobile space has moved from 1:1 to 4:1, so possibly 3/4 of the (possible) users will be lost by doing this. However, 8.1 end-of-support appears to be in a week, so maybe we should do this.

[sourceomatic]

It would be OK to add a Universal app, but please don't go to ONLY universal. I have several Lumias that were not vendor-supported for Win10M, and are stuck on WinPhone 8.1 until they die. Unfortunately I'm stuck using them until they die (long story as to why!) and I'd really miss this app!