Added msbuild targets -

Before build:
* build belle
* generate json schema

After clean:
* Remove belle
* Remove json schema

src/Umbraco.Web.UI.NetCore/Umbraco.Web.UI.NetCore.csproj

@@ -27,8 +27,8 @@
   <ItemGroup>
     <Compile Remove="umbraco\Data\**" />
     <Compile Remove="umbraco\logs\**" />
-    <Compile Remove="umbraco\MediaCache\**" />
-    <Compile Remove="wwwroot\Umbraco\**" />
+    <Compile Remove="umbraco\mediacache\**" />
+    <Compile Remove="wwwroot\umbraco\**" />
     <Compile Remove="App_Data\**" />
   </ItemGroup>
 
@@ -36,14 +36,14 @@
     <EmbeddedResource Remove="App_Data\**" />
     <EmbeddedResource Remove="umbraco\Data\**" />
     <EmbeddedResource Remove="umbraco\logs\**" />
-    <EmbeddedResource Remove="umbraco\MediaCache\**" />
+    <EmbeddedResource Remove="umbraco\mediacache\**" />
   </ItemGroup>
 
   <ItemGroup>
     <Content Remove="App_Data\**" />
     <Content Remove="umbraco\Data\**" />
     <Content Remove="umbraco\logs\**" />
-    <Content Remove="umbraco\MediaCache\**" />
+    <Content Remove="umbraco\mediacache\**" />
     <Content Remove="wwwroot\Web.config" />
   </ItemGroup>
 
@@ -60,7 +60,7 @@
     <None Remove="App_Data\**" />
     <None Remove="umbraco\Data\**" />
     <None Remove="umbraco\logs\**" />
-    <None Remove="umbraco\MediaCache\**" />
+    <None Remove="umbraco\mediacache\**" />
     <None Include="umbraco\UmbracoWebsite\NoNodes.cshtml" />
   </ItemGroup>
 
@@ -81,5 +81,46 @@
     <RazorCompileOnBuild>false</RazorCompileOnBuild>
     <RazorCompileOnPublish>false</RazorCompileOnPublish>
   </PropertyGroup>
+  
+  <PropertyGroup>
+    <BellePath>$(ProjectDir)wwwroot\umbraco</BellePath>
+    <JsonSchemaPath>$(ProjectDir)umbraco\config\appsettings-schema.json</JsonSchemaPath>
+  </PropertyGroup>
+  <Target Name="CheckPreconditions" BeforeTargets="Build">
+    <Message Text="-CheckPreconditions-" Importance="high" />
+    <Message Text="JsonSchemaPath:  $(JsonSchemaPath)" Importance="high" />
+    <Message Text="BellePath:       $(BellePath)" Importance="high" />
 
+   <!-- Build Belle, if building is Visual Studio and the build folder does not exist yet -->
+    <Message Text="Skip Belle because UmbracoBuild is '$(UmbracoBuild)' (this is not Visual Studio)." Importance="High" Condition="'$(UmbracoBuild)' != ''" />
+    <Message Text="Skip Belle because $(BellePath) exists." Importance="High" Condition="Exists('$(BellePath)')" />
+    <Message Text="Build Belle because UmbracoBuild is empty (this is Visual Studio), and $(BellePath) does not exist." Importance="High" Condition="!Exists('$(BellePath)') and '$(UmbracoBuild)' == ''" />
+    <CallTarget Targets="BelleBuild" Condition="!Exists('$(BellePath)') and '$(UmbracoBuild)' == ''" />
+
+    <Message Text="Skip JsonSchema generation because $(JsonSchemaPath) exists." Importance="High" Condition="Exists('$(JsonSchemaPath)')" />
+    <Message Text="Generate the appsettings json schema." Importance="High" Condition="!Exists('$(JsonSchemaPath)') and '$(UmbracoBuild)' == ''" />
+
+    <CallTarget Targets="JsonSchemaBuild" Condition="!Exists('$(JsonSchemaPath)') and '$(UmbracoBuild)' == ''" />
+  </Target>
+  <Target Name="BelleBuild">
+    <Exec WorkingDirectory="$(ProjectDir)\..\..\" Command="powershell -ExecutionPolicy RemoteSigned -Command &quot;&amp;{ $ubuild = &amp;&quot;$pwd\build\build.ps1&quot; -get ; $ubuild.CompileBelle() }&quot;" />
+  </Target>
+  <Target Name="JsonSchemaBuild">
+    <Exec WorkingDirectory="$(ProjectDir)\..\..\" Command="powershell -ExecutionPolicy RemoteSigned -Command &quot;&amp;dotnet run --project $pwd\src\JsonSchema\JsonSchema.csproj -c Release -- --outputFile $pwd\src\Umbraco.Web.UI.NetCore\$(JsonSchemaPath) &quot;" />
+  </Target>
+  
+  <!-- clean Belle when cleaning and rebuilding, but only in Visual Studio -->
+  <Target Name="CleanPreconditions" AfterTargets="Clean" Condition="'$(UmbracoBuild)' == ''">
+    <Message Text="-CleanPreconditions-" Importance="high" />
+    <Message Text="Nothing to clean, as $(BellePath) does not exist." Importance="High" Condition="!Exists('$(BellePath)')" />
+    <Message Text="Not cleaning (found src/preserve.belle)." Importance="High" Condition="Exists('$(BellePath)') and Exists('$(SolutionDir)preserve.belle')" />
+    <Message Text="Remove $(BellePath)." Importance="High" Condition="Exists('$(BellePath)') and !Exists('$(SolutionDir)preserve.belle')" />
+    <ItemGroup>
+      <BelleLib Include="$(BellePath)" />
+    </ItemGroup>
+    <RemoveDir Directories="@(BelleLib)" Condition="Exists('$(BellePath)') and !Exists('$(SolutionDir)preserve.belle')" />
+
+    <Message Text="Remove $(JsonSchemaPath)." Importance="High" Condition="Exists('$(JsonSchemaPath)') and !Exists('$(SolutionDir)preserve.jsonschema')" />
+    <Delete Files="$(JsonSchemaPath)"  Condition="Exists('$(JsonSchemaPath)') and !Exists('$(SolutionDir)preserve.jsonschema')"/>
+  </Target>
 </Project>