Restore option to load assembly into the current AppDomain

Fixes #169

Happy to refactor and/or add tests as needed.

Mono.TextTemplating/Mono.TextTemplating/CompiledTemplate.TemplateExecutor.cs

@@ -17,13 +17,16 @@ partial class CompiledTemplate
 	class TemplateProcessor : MarshalByRefObject
 	{
 		[SuppressMessage ("Performance", "CA1822:Mark members as static", Justification = "Needs to be an instance for MarshalByRefObject")]
-		public string CreateAndProcess (ITextTemplatingEngineHost host, CompiledAssemblyData templateAssemblyData, string templateAssemblyFile, string fullName, CultureInfo culture, string[] referencedAssemblyFiles)
+		public string CreateAndProcess (ITextTemplatingEngineHost host, CompiledAssemblyData templateAssemblyData, string templateAssemblyFile, string fullName, CultureInfo culture, string[] referencedAssemblyFiles, bool loadAssemblyIntoAppDomain)
 		{
 			using var context = new TemplateAssemblyContext (host, referencedAssemblyFiles);
 
-			Assembly assembly = templateAssemblyData is not null
-				? context.LoadInMemoryAssembly (templateAssemblyData)
-				: context.LoadAssemblyFile (templateAssemblyFile);
+			Assembly assembly =
+				templateAssemblyData is not null
+					? loadAssemblyIntoAppDomain
+						? Assembly.Load (templateAssemblyData.Assembly)
+						: context.LoadInMemoryAssembly (templateAssemblyData)
+					: context.LoadAssemblyFile (templateAssemblyFile);
 
 			// MS Templating Engine does not care about the type itself
 			// it only requires the expected members to be on the compiled type

Mono.TextTemplating/Mono.TextTemplating/CompiledTemplate.cs

@@ -105,9 +105,12 @@ TemplateProcessor CreateTemplateProcessor ()
 #endif
 
 		public string Process ()
+			=> Process (loadAssemblyIntoAppDomain: false);
+
+		public string Process (bool loadAssemblyIntoAppDomain)
 		{
 			TemplateProcessor processor = CreateTemplateProcessor ();
-			return processor.CreateAndProcess (host, templateAssemblyData, templateAssemblyFile, templateClassFullName, culture, ReferencedAssemblyFiles);
+			return processor.CreateAndProcess (host, templateAssemblyData, templateAssemblyFile, templateClassFullName, culture, ReferencedAssemblyFiles, loadAssemblyIntoAppDomain);
 		}
 
 		public void Dispose ()