Remove Serilog and GitHub.Extensions dependencies

Make it so that the *DictionaryManager code doesn't depend on Serilog,
GitHub.Logging and GitHub.Extensions. This fixes tests executed using
NCrunch in a new app domain (where the NCrunch assembly resolved isn't
installed).
LoadingResourceDictionary now uses Trace.WriteLine for logging, which
should also work when executing in design mode.

Author: jcansdale

src/GitHub.UI/Helpers/LoadingResourceDictionary.cs

@@ -3,14 +3,12 @@
 using System.Windows;
 using System.Reflection;
 using System.Collections.Generic;
-using GitHub.Logging;
-using Serilog;
+using System.Diagnostics;
 
 namespace GitHub
 {
     public class LoadingResourceDictionary : ResourceDictionary
     {
-        static readonly ILogger log = LogManager.ForContext<LoadingResourceDictionary>();
         static Dictionary<string, Assembly> assemblyDicts = new Dictionary<string, Assembly>();
 
         public new Uri Source
@@ -31,7 +29,7 @@ void EnsureAssemblyLoaded(Uri value)
                 var assemblyName = FindAssemblyNameFromPackUri(value);
                 if (assemblyName == null)
                 {
-                    log.Error("Couldn't find assembly name in '{Uri}'", value);
+                    Trace.WriteLine($"Couldn't find assembly name in '{value}'");
                     return;
                 }
 
@@ -44,16 +42,16 @@ void EnsureAssemblyLoaded(Uri value)
 
                 if (!File.Exists(assemblyFile))
                 {
-                    log.Error("Couldn't find assembly at '{AssemblyFile}'", assemblyFile);
+                    Trace.WriteLine($"Couldn't find assembly at '{assemblyFile}'");
                     return;
                 }
 
                 var assembly = Assembly.LoadFrom(assemblyFile);
                 assemblyDicts.Add(assemblyFile, assembly);
             }
-            catch(Exception e)
+            catch (Exception)
             {
-                log.Error(e, "Error loading assembly for '{Uri}'", value);
+                Trace.WriteLine($"Error loading assembly for '{value}");
             }
         }
 

src/GitHub.UI/Helpers/SharedDictionaryManager.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Windows;
 using System.Collections.Generic;
-using GitHub.Extensions;
 using System.Globalization;
 
 namespace GitHub.UI.Helpers
@@ -17,8 +16,6 @@ public SharedDictionaryManager() : this(CachingFactory.GetInstanceForDomain())
 
         public SharedDictionaryManager(CachingFactory factory)
         {
-            Guard.ArgumentNotNull(factory, nameof(factory));
-
             this.factory = factory;
         }
 
@@ -77,9 +74,6 @@ public static CachingFactory GetInstanceForDomain()
 
             public ResourceDictionary GetOrCreateResourceDictionary(ResourceDictionary owner, Uri uri)
             {
-                Guard.ArgumentNotNull(owner, nameof(owner));
-                Guard.ArgumentNotNull(uri, nameof(uri));
-
                 TryAddDisposable(owner);
 
                 ResourceDictionary rd;
@@ -95,8 +89,6 @@ public ResourceDictionary GetOrCreateResourceDictionary(ResourceDictionary owner
             // Remember subtypes that need disposing of.
             public void TryAddDisposable(object owner)
             {
-                Guard.ArgumentNotNull(owner, nameof(owner));
-
                 var disposable = owner as IDisposable;
                 if (disposable != null)
                 {
@@ -132,8 +124,6 @@ public void Dispose()
 
         public static Uri FixDesignTimeUri(Uri inUri)
         {
-            Guard.ArgumentNotNull(inUri, nameof(inUri));
-
             if (inUri.Scheme != "file")
             {
                 return inUri;