Regenerate gradle wrappers used in Android builds

Fix policy files creation and install

Add Swift Package Manager sources

Update Swift version to 3.7b2

Fix iOS build

Add Visual Studio 2019 NuGet packaging files

Another fix for Slice/errorDetection

Missing quotes

Update JAR version to 3.7.1-1

PyThread_get_thread_ident returns unsigned long in Python 3.7 and lon…

…g in older versions