Fix #1399: Use same default value as in previous versions for "show internal types and members" setting. Fixes #1398 as well.

ILSpy/FilterSettings.cs

@@ -36,7 +36,7 @@ namespace ICSharpCode.ILSpy
 	{
 		public FilterSettings(XElement element)
 		{
-			this.ShowApiLevel = (ApiVisibility?)(int?)element.Element("ShowAPILevel") ?? ApiVisibility.PublicOnly;
+			this.ShowApiLevel = (ApiVisibility?)(int?)element.Element("ShowAPILevel") ?? ApiVisibility.PublicAndInternal;
 			this.Language = Languages.GetLanguage((string)element.Element("Language"));
 			this.LanguageVersion = Language.LanguageVersions.FirstOrDefault(v => v.Version == (string)element.Element("LanguageVersion"));
 			if (this.LanguageVersion == default(LanguageVersion))