* Updated all the OpenTK references to use NuGet
- Using the same NuGet version of OpenTK across the board
- Added a gallery factory to allow for platform-specific pages
- Added the OpenGL galleries to Android, iOS, GTK# and WPF
* Fix the build for iOS and macOS
* Fix the modified defines for the control gallery
* Add RegistrarValidationService to test presence of renderers
* [iOS] Restore NativeViewWrapper registration
fixes#2757
* [Android] Prevent NRE in ListViewAdapter