Merge branch 'maintenance/flatten-namespaces' into develop

In the name of organization, we've created a relatively granular folder structure. And, by convention, we've mapped our namespaces to those folders. Generally, that's a good practice. But useful file organization is different from useful namespace organization. As such, I've differentiated between the two by introducing `_camelCase` folders whose types are part of the parent namespace, but allow related files to be grouped on the file system. As part of this, I've collapsed the `OnTopic.ViewModels.Items` and `OnTopic.ViewModels.Collections` back into the `OnTopic.ViewModels` namespace. I've also created the `/OnTopic/Mapping/_exceptions`, `/OnTopic/Repositories/_exceptions`, and `/OnTopic/Repositories/_eventArgs` folders for collecting exception and events argument classes without altering their namespaces.

None of this will impact OnTopic 4.0.0 migrations, since e.g. the `OnTopic.ViewModels` namespace was originally flat. It might break early integrations of the preview releases of OnTopic, though.

Author: JeremyCaney

OnTopic.Tests/TopicMappingServiceTest.cs

@@ -23,7 +23,6 @@
 using OnTopic.Tests.ViewModels;
 using OnTopic.Tests.ViewModels.Metadata;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Items;
 
 namespace OnTopic.Tests {
 

OnTopic.Tests/ViewModels/DescendentTopicViewModel.cs

@@ -5,7 +5,6 @@
 \=============================================================================================================================*/
 using OnTopic.Mapping.Annotations;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Collections;
 
 namespace OnTopic.Tests.ViewModels {
 

OnTopic.Tests/ViewModels/FilteredContentTypeTopicViewModel.cs

@@ -5,7 +5,6 @@
 \=============================================================================================================================*/
 using OnTopic.Mapping.Annotations;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Collections;
 
 namespace OnTopic.Tests.ViewModels {
 

OnTopic.Tests/ViewModels/FilteredInvalidTopicViewModel.cs

@@ -5,7 +5,6 @@
 \=============================================================================================================================*/
 using OnTopic.Mapping.Annotations;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Collections;
 
 namespace OnTopic.Tests.ViewModels {
 

OnTopic.Tests/ViewModels/FilteredTopicViewModel.cs

@@ -5,7 +5,6 @@
 \=============================================================================================================================*/
 using OnTopic.Mapping.Annotations;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Collections;
 
 namespace OnTopic.Tests.ViewModels {
 

OnTopic.Tests/ViewModels/MetadataLookupTopicViewModel.cs

@@ -5,7 +5,6 @@
 \=============================================================================================================================*/
 using OnTopic.Mapping.Annotations;
 using OnTopic.ViewModels;
-using OnTopic.ViewModels.Collections;
 
 namespace OnTopic.Tests.ViewModels {
 

OnTopic.ViewModels/ContentListTopicViewModel.cs

@@ -3,8 +3,6 @@
 | Client        Ignia, LLC
 | Project       Topics Library
 \=============================================================================================================================*/
-using OnTopic.ViewModels.Collections;
-using OnTopic.ViewModels.Items;
 
 namespace OnTopic.ViewModels {
 

OnTopic.ViewModels/TopicViewModelLookupService.cs

@@ -7,7 +7,6 @@
 using System.Collections.Generic;
 using System.Reflection;
 using OnTopic.Lookup;
-using OnTopic.ViewModels.Items;
 
 namespace OnTopic.ViewModels {
 

…/Collections/TopicViewModelCollection.cs …_collections/TopicViewModelCollection.csOnTopic.ViewModels/Collections/TopicViewModelCollection.cs renamed to OnTopic.ViewModels/_collections/TopicViewModelCollection.cs OnTopic.ViewModels/Collections/TopicViewModelCollection.cs renamed to OnTopic.ViewModels/_collections/TopicViewModelCollection.cs

@@ -10,7 +10,7 @@
 using OnTopic.Internal.Diagnostics;
 using OnTopic.Models;
 
-namespace OnTopic.ViewModels.Collections {
+namespace OnTopic.ViewModels {
 
   /*============================================================================================================================
   | VIEW MODEL: TOPIC COLLECTION

…odels/Items/ContentItemTopicViewModel.cs …dels/_items/ContentItemTopicViewModel.csOnTopic.ViewModels/Items/ContentItemTopicViewModel.cs renamed to OnTopic.ViewModels/_items/ContentItemTopicViewModel.cs OnTopic.ViewModels/Items/ContentItemTopicViewModel.cs renamed to OnTopic.ViewModels/_items/ContentItemTopicViewModel.cs

@@ -5,7 +5,7 @@
 \=============================================================================================================================*/
 using System;
 
-namespace OnTopic.ViewModels.Items {
+namespace OnTopic.ViewModels {
 
   /*============================================================================================================================
   | VIEW MODEL: CONTENT ITEM TOPIC