Update changelog for 5.1.1 release

Update changelog for 5.1.0 release

Update changelog

Update changelog for 5.0.0 release

Update changelog

Update changelog for 4.4.0

Update changelog for 4.3.1

Add 4.3.0 version header with release date

Add 4.2.1 to changelog

Fix explicit NuGet version tool corrupting package

UTF-16 in the nuspec won't load with NuGet, so force it to UTF-8.