Fix VS2017 build integration using redirect targets

VS2017 has privatized MSBuild in such a way that it cannot see the
installed WiX Toolset build tools. Therefore we add targets to our VSIX
to do the work to find the actual installed WiX Toolset build tools.

Author: robmen

src/Votive2017/Votive2017.csproj

@@ -26,6 +26,19 @@
     <None Include="source.extension.vsixmanifest" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Include="redirects\v3\wix.targets">
+      <IncludeInVSIX>true</IncludeInVSIX>
+      <InstallRoot>MSBuild</InstallRoot>
+      <VSIXSubPath>Microsoft\WiX\v3.x\</VSIXSubPath>
+    </Content>
+    <Content Include="redirects\v4\wix.targets">
+      <IncludeInVSIX>true</IncludeInVSIX>
+      <InstallRoot>MSBuild</InstallRoot>
+      <VSIXSubPath>WiX Toolset\v4\</VSIXSubPath>
+    </Content>
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\votive\votive.csproj">
       <Project>{24A98296-9D58-42C1-95C0-CC36736409E2}</Project>

src/Votive2017/redirects/v3/wix.targets

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" InitialTargets="EnsureActualWixToolsetInstalled" ToolsVersion="15.0">
+  <PropertyGroup>
+    <WixMSBuildFolder>$(MSBuildProgramFiles32)\MSBuild\Microsoft\WiX\v3.x\</WixMSBuildFolder>
+  </PropertyGroup>
+
+  <Import Project="$(WixMSBuildFolder)wix.targets" Condition=" Exists('$(WixMSBuildFolder)wix.targets') " />
+  <Target Name="EnsureActualWixToolsetInstalled" Condition=" !Exists('$(WixMSBuildFolder)wix.targets') ">
+    <Error Text="The WiX Toolset v3 build tools must be installed to build this project. Could not find wix.targets at '$(WixMSBuildFolder)'. To download WiX Toolset v3, see http://wixtoolset.org/releases/" />
+  </Target>
+</Project>

src/Votive2017/redirects/v4/wix.targets

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" InitialTargets="EnsureActualWixToolsetInstalled" ToolsVersion="15.0">
+  <PropertyGroup>
+    <WixInstallFolder>$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\WiX Toolset\v4', 'InstallFolder', null, RegistryView.Registry32))</WixInstallFolder>
+  </PropertyGroup>
+
+  <Import Project="$(WixInstallFolder)bin\wix.targets" Condition=" Exists('$(WixInstallFolder)bin\wix.targets') " />
+  <Target Name="EnsureActualWixToolsetInstalled" Condition=" !Exists('$(WixInstallFolder)bin\wix.targets') ">
+    <Error Text="The WiX Toolset v4 build tools must be installed to build this project. Could not find wix.targets at '$(WixInstallFolder)'. To download WiX Toolset v4, see http://wixtoolset.org/releases/" />
+  </Target>
+</Project>

src/Votive2017/source.extension.vsixmanifest

@@ -11,7 +11,7 @@
   <Dependencies>
     <Dependency Id="Microsoft.Framework.NDP" DisplayName="Microsoft .NET Framework" d:Source="Manual" Version="[4.0,)" />
   </Dependencies>
-  <Installation>
+  <Installation AllUsers="true">
     <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[15.0,16.0)" />
   </Installation>
   <Assets>