better project structure, UWP fixes, sample addings

[tuke307]

:sparkles: What kind of change does this PR introduce? (Bug fix, feature, docs update...)

After the issue #777 and its corresponding stackoverflow question I was worried about what is going wrong here.

I tested a few previous versions and found out since version 0.9.9 the UAP version is not working. The Target Version was downgraded from UAP 10.0.18362.0(Version 1903) to 10.0.17763(Version 1809) from version 0.9.7 to 0.9.9.

See my commit titles for change description.

:arrow_heading_down: What is the current behavior?

• UAP not working with v. 17763
• no WPF samples

:new: What is the new behavior (if this is a feature change)?

• working UAP with v. 18362
• better structure in .csproj files
• implemented WPF projects with connected viewmodels

:boom: Does this PR introduce a breaking change?

no

:bug: Recommendations for testing

Because of the media element error while streaming from http source, the wpf sample project samples crashed immediately when navigating to the player view. I will create some real wpf samples in the future/ add an error handling method for HTTP/S sources.

:memo: Links to relevant issues/docs

777

stackoverflow question

:thinking: Checklist before submitting

• [x] All projects build
• [x] Follows style guide lines
• [x] Relevant documentation was updated
• [x] Rebased onto current develop

[martijn00]

I can't update the UWP target at the moment in the project itself, but setting it as target on the app should work i think. Otherwise most changes look good. I'll merge and do some more changes myself. Can you test again after that?