Add support for .NET Standard 1.x and Portable Class Library

[LonghronShen]

Add support for .NET Standard 1.x and Portable Class Library
Note Since .NET Standard 2.0 has added support for ANSI based encodings for asian languages, so this package is not required for that platform.

[Beyley]

Sorry for the few year bump, but i was wondering if this could be merged an uploaded to Nuget, as my project uses dotnet 5.0 and i get a build warning because the project technechally isnt "net5.0 compatible" when it works just fine

[jstedfast]

@Beyley why do you need this for net50? Why not use https://www.nuget.org/packages/System.Text.Encoding.CodePages ?

[Beyley]

@Beyley why do you need this for net50? Why not use https://www.nuget.org/packages/System.Text.Encoding.CodePages ?

well I didn't know that existed lol thanks for letting me know

[jstedfast]

@Beyley

Add a reference to that nuget and then, in your "Main()" method (or wherever you do initialization for your app), do:

System.Text.Encoding.RegisterProvider (System.Text.CodePagesEncodingProvider.Instance);

Or, if your project is a multi-targeted library, what I do is this:

#if NETSTANDARD || NET5_0_OR_GREATER
	var encodingProviderType = typeof (Encoding).Assembly.GetType ("System.Text.EncodingProvider");
	var registerProvider = typeof (Encoding).GetMethod ("RegisterProvider", new Type[] { encodingProviderType });
	if (registerProvider != null) {
		try {
			var assembly = Assembly.Load ("System.Text.Encoding.CodePages");
			if (assembly != null) {
				var providerType = assembly.GetType ("System.Text.CodePagesEncodingProvider");
				var property = providerType.GetProperty ("Instance").GetGetMethod ();
				var instance = property.Invoke (providerType, new object[0]);

				registerProvider.Invoke (typeof (Encoding), new object[] { instance });
			}
		} catch (FileNotFoundException) {
		}
	}
#endif

[jstedfast]

Oops, didn't mean to close this.