Add engine nuget package

NUnit.proj

@@ -467,6 +467,17 @@
 
   </Target>
 
+  <Target Name="PackageNugetEngine" Label="Creates the NUnit.Engine NuGet package"
+      DependsOnTargets="_CreateImageIfNotPresent">
+    <Message Text="******************************************************************" />
+    <Message Text="* Creating the NUnit.Engine Nuget $(Configuration) package" />
+    <Message Text="******************************************************************" />
+
+    <Exec WorkingDirectory="$(ProjectBaseDir)"
+        Command="$(ManagedExeLauncher) &quot;$(NugetExecutable)&quot; pack $(NuspecDirectory)\nunit.engine.nuspec -NoPackageAnalysis -BasePath &quot;$(CurrentImageDir)&quot; -OutputDirectory &quot;$(ProjectPackageDir)&quot; -Properties version=$(NugetVersion)" />
+
+  </Target>
+
   <Target Name="PackageMsi" Label="Creates the master MSI installer for NUnit"
       DependsOnTargets="_CreateImageIfNotPresent">
     <MSBuild Targets="Rebuild" Projects="$(InstallDir)\master\nunit.wixproj"

nuget/nunit.engine.nuspec

@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
+  <metadata>
+    <id>NUnit.Engine</id>
+    <title>NUnit Test Engine</title>
+    <version>$version$</version>
+    <authors>Charlie Poole</authors>
+    <owners>Charlie Poole</owners>
+    <licenseUrl>http://nunit.org/nuget/nunit3-license.txt</licenseUrl>
+    <projectUrl>http://nunit.org</projectUrl>
+    <iconUrl>http://nunit.org/nuget/nunitv3_32x32.png</iconUrl>
+    <requireLicenseAcceptance>false</requireLicenseAcceptance>
+    <summary>The NUnit Test Engine is used by runners to discover and execute tests.</summary>
+    <description>This package includes nunit.engine and related assemblies, for use by runner programs. It is not intended for direct use by users who simply want to run tests.</description>
+    <releaseNotes></releaseNotes>
+    <language>en-US</language>
+    <tags>nunit test testing tdd engine</tags>
+    <copyright>Copyright (c) 2015 Charlie Poole</copyright>
+  </metadata>
+  <files>
+    <file src="LICENSE.txt" />
+    <file src="NOTICES.txt" />
+    <file src="CHANGES.txt" />
+    <file src="bin\nunit.engine.dll" target="lib" />
+    <file src="bin\nunit.engine.api.dll" target="lib" />
+    <file src="bin\Mono.Cecil.dll" target="lib" />
+    <file src="bin\nunit-agent.exe" target="lib" />
+    <file src="bin\nunit-agent.exe.config" target="lib" />
+    <file src="bin\nunit-agent-x86.exe" target="lib" />
+    <file src="bin\nunit-agent-x86.exe.config" target="lib" />
+  </files>
+</package>