Update to Toolkit v3.8

[FroggieFrog]

This PR adds the latest code available under the MS-PL license to the master branch.

[jogibear9988]

are you sure 3.8 was still mspl?

[FroggieFrog]

I'm pretty sure. The developer is backing this in this issue: xceedsoftware/wpftoolkit#1655
and also here: xceedsoftware/wpftoolkit#1616

[FroggieFrog]

Can I do anything to get this merged and trigger new release?

[jogibear9988]

1.) The Pull request need to build on appveyor, at the moment it does not.
2.) The Release is always build from the extened branch. The Extended Branch contains many fixes, so the master needs to be merged to extended

[Houzvicka]

@FroggieFrog, @jogibear9988 Is there any chance you still plan to work on it and merge it?
I would love to use it in my project but I need fixes that are made in version 3.8.
Thanks

[jogibear9988]

@FroggieFrog, @jogibear9988 Is there any chance you still plan to work on it and merge it? I would love to use it in my project but I need fixes that are made in version 3.8. Thanks

I do not plan to work on it.

if you work on it, I could merge when it compiles

[Houzvicka]

@jogibear9988 you can find it here :) #41