Add PackageFile build action support to package project

Also make the default included readme a package file instead.

Author: kzu

src/VisualStudio/NuGet.Packaging.VisualStudio.15/Templates/Projects/Nuget/Package/Package.nuproj

@@ -29,10 +29,7 @@
 	<PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|AnyCPU'" />
 
 	<ItemGroup>
-		<None Include="Readme.txt">
-			<IncludeInPackage>true</IncludeInPackage>
-			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-		</None>
+		<PackageFile Include="Readme.txt" />
 	</ItemGroup>
 
 	<Import Project="$(MSBuildToolsPath)\Microsoft.Common.targets" />

src/VisualStudio/NuGet.Packaging.VisualStudio/NuGet.Packaging.VisualStudio.csproj

@@ -182,6 +182,10 @@
       <SubType>Designer</SubType>
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Rules\PackageFile.xaml">
+      <SubType>Designer</SubType>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Page Include="Views\AddPlatformImplementationView.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>

src/VisualStudio/NuGet.Packaging.VisualStudio/Rules/PackageFile.xaml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Rule Name="PackageFile"
+      DisplayName="Package File"
+      PageTemplate="generic"
+      Description="Package file items"
+      xmlns="http://schemas.microsoft.com/build/2009/properties">
+
+	<Rule.DataSource>
+		<DataSource Persistence="ProjectFile"
+                    HasConfigurationCondition="False"
+                    ItemType="PackageFile" />
+	</Rule.DataSource>
+	<Rule.Categories>
+		<Category Name="Advanced"
+                  DisplayName="Advanced" />
+		<Category Name="Misc"
+                  DisplayName="Misc" />
+	</Rule.Categories>
+
+	<DynamicEnumProperty Name="{}{ItemType}"
+                         DisplayName="Build Action"
+                         Category="Advanced"
+                         Description="How the file relates to the build and deployment processes."
+                         EnumProvider="ItemTypes" />
+
+	<StringProperty Name="Identity"
+                    DisplayName="File Name"
+                    ReadOnly="true"
+                    Category="Misc"
+                    Description="Name of the file or folder.">
+		<StringProperty.DataSource>
+			<DataSource Persistence="Intrinsic"
+                        ItemType="PackageFile"
+                        PersistedName="Identity" />
+		</StringProperty.DataSource>
+	</StringProperty>
+
+	<StringProperty Name="FullPath"
+                    DisplayName="Full Path"
+                    ReadOnly="true"
+                    Category="Misc"
+                    Description="Location of the file.">
+		<StringProperty.DataSource>
+			<DataSource Persistence="Intrinsic"
+                        ItemType="PackageFile"
+                        PersistedName="FullPath" />
+		</StringProperty.DataSource>
+	</StringProperty>
+
+	<BoolProperty Name="Visible"
+                  Visible="false" />
+	<StringProperty Name="Link"
+                    Visible="false" />
+	<StringProperty Name="Extension"
+                    Visible="False">
+		<StringProperty.DataSource>
+			<DataSource Persistence="Intrinsic"
+                        ItemType="PackageFile"
+                        PersistedName="Extension" />
+		</StringProperty.DataSource>
+	</StringProperty>
+</Rule>

src/VisualStudio/NuGet.Packaging.VisualStudio/Rules/ProjectItemsSchema.xaml

@@ -1,7 +1,15 @@
 <?xml version="1.0" encoding="utf-8"?>
 <ProjectSchemaDefinitions xmlns="http://schemas.microsoft.com/build/2009/properties">
 
-    <ItemType Name="None"
+	<ItemType Name="PackageFile"
+              DisplayName="Package File" />
+
+	<ContentType Name="PackageFile"
+                 DisplayName="Package File"
+                 ItemType="PackageFile">
+	</ContentType>
+
+	<ItemType Name="None"
               DisplayName="None" />
 
     <ItemType Name="Content"

src/VisualStudio/NuGet.Packaging.VisualStudio/Targets/NuGet.Packaging.Authoring.targets

@@ -35,6 +35,7 @@ Copyright (c) .NET Foundation. All rights reserved.
       <Context>BrowseObject</Context>
     </PropertyPageSchema>
     <PropertyPageSchema Include="
+							$(ProjectSystemRulesDir)PackageFile.xaml;
 							$(ProjectSystemRulesDir)folder.xaml;
 							$(ProjectSystemRulesDir)none.xaml;
 							$(ProjectSystemRulesDir)content.xaml">