Initial commit of "NuProj", an MSBuild integration for NuGet.
Add setup
Add missing default for property NuProjTasksPath
Fix Clean target to not just delete output and intermediate directories

In general, Clean should only clean up pieces produced by the build.
This way, when dropping to shared directories, builds don't delete
artifacts produced by other builds.
Redirect IntermediateOutputPath to project root
Align order of target names in MSBuild calls so they are consistent
Make build resilient to changes to the build projects
Add template for 'File | New' to setup
Reorder properties to make flow more logical
Fix nuspec generation to use FrameworkReferences instead of References
Update NuGetPackage.nuproj template

Include more comments and a link to the documentation.
Update assembly info
Make build more sophisticated

Add support for dropping release bits, i.e. zip archives.
Add support for injecting custom "before" and "after" targets
Add scripts for installing and uninstalling
Fix typo in variable name
Add documentation
Add support for generating symbol packages
Add basic support <ProjectReference> elements
Add support for referencing other .nuproj files

This is a very convenient way to declare dependencies to NuGet packages
that are being produced by the same build.