This should either be defined globally or not at all.  Repeating all the logic on a local level is just wasted time.

TLDR: artifacts are going to move around in Binaries\Debug and the directory is going to get a lot bigger.

At a high level build projects can be classified into three categories based on how they write output:

- incorrect: a given output path is written to more than once with different contents
- less correct: a given output path is written to more than once but always with the same content
- correct: a given output path is written to exactly once

Today the roslyn build is decidedly “incorrect” as pretty much every file is written directly into Binaries\Debug. This means it ends up writing pretty much every Visual Studio SDK DLL twice: once for Dev14 and once for Dev15. For example at various points in the build Binaries\Debug\Microsoft.VisualStudio.Text.Data.dll may refer to Dev14 and at others it’s Dev15. If this seems like a scary proposition for a build that’s because it is indeed scary and it has real consequences. By now pretty much everyone on the team has hit the build race condition that is dragging down our PRs.

The general fix here is to move build outputs into separate directories. Instead of building to $(Configuration) projects now build into say $(Configuration)\Exes\$(MSBuildProjectFileName). This will have a substantial increase in the size of Binaries. We will be looking into ways to reduce that. In the short term though build stability far outweighs the size increase.

This change takes us most of the way to "correct". There are several places I had to compromise in order to get this initial change in:

- UnitTests still build to a common output folder (one for Dev14, another for Dev15). Pulling unit tests apart is going to take a bit of work.
- Every project has a <RoslynProjectType> entry. This will go away in the future for most projects. It's temporarily needed so I can fix roslyn-internal in parallel without taking down the build.
- VSL.Imports.targets is messy. Unavoidable for now due to the above. It will get cleaner as I iterate on this.

None of these are relevant to the underlying race condition. Hence it's okay to push them off.

The ImportGroup element is just noise.  It was also used very inconsistently in the repo and often within the same project file.  Just remove it.

The dependency projects serve a few purposes:

- Help ensure package unity by serving as a single place for a NuGet reference.
- Make NuGet updates simple by having a single place to change.
- Grouping together related packages to make it easy to take a dependency on say Visual Studio editor.

The first two points are largely obsolete now that our project.json references are strictly validated on every build and have a single update mechanism.  This meant a lot of our depnedency projects were just making Roslyn.sln bigger.

As such I went through and deleted all of them which had only 1 or 2 project.json entries.  I left the VS ones which tend to group 10+ references together.  They are still serving a valid "reference VS" purpose.

* Enable building and testing on machines with only Dev15 Preview 3 installed

1. Auto-detect the VS common tools path
2. Convert analyzer samples to import Roslyn targets
3. Ensure dependencies are copied to the output directory
4. Workaround: Use local Microsoft.Net.Compilers.props until we move to a compiler toolset with https://github.com/dotnet/roslyn/commit/05c12ebfcdd08a02dbceded5327a8da7a7df23be
5. Replace references to Microsoft.VisualStudio.ComponentModelHost.dll (VisualStudioReferenceAssemblyVersion) with a nuget reference to RoslynDependencies.Microsoft.VisualStudio.ComponentModelHost
6. Add nuget references to Roslyn.Microsoft.Build, Roslyn.Microsoft.VisualStudio.ExtensionManager, RoslynDependencies.Microsoft.VisualStudio.Diagnostics.PerformanceProvider and RoslynDependencies.Microsoft.VisualStudio.CodeAnalysis.Sdk.UI.

* Remove workaround now that new NuGet packages have been uploaded to nuget.org

* Remove preprocessor directive MSBUILD12 and its references

This reverts commit 31377ce7.

Update TargetFrameworkVersions.

Since #f9b4d71a, tests inherit app.config if they don't specify one. Removed the ones that match the default behavior.

by removing `<DebugType>` lines from projects that import `VSL.Settings.targets`

Ensured that all uses of app.config in our product / test code base is
used in the lower case form.  This helps with our Unix efforts where
mixing the case can be significant.  Updated all of the project
references to ensure they used the lower case version as well.

Moved the MSBuild tests into the appropriate DLL

Moves the build task code to a shared project that we use to build
at net45 and a portable50 CodeAnalysis MSBuild task. Also upgrades to
nuget v3.2.1-rc since this is necessary to understand the dotnet4.3 spec
used in the project.json.

The native compiler handled corrupted default parameter values by
substituting in default(T).  It's unclear if this was intentional
behavior in the compiler or not.

Either way though obfuscators took advantage of this behavior and at
least one prominent one will corrupt default parameter values when the
value is null.  Enough prominent libraries have shipped using such
obfuscators that it is a blocker to upgrading.  Hence we need to emulate
the native compiler behavior here.

This change is a bit large because I needed to update the test resources
with a corrupted DLL in order to test out the changes.

closes #4196

Move TestUtilities.csproj and TestUtilities.FX45.csproj to separate directories to accomodate current nuget limitations

This updates the referenced version of 'Microsoft.CodeAnalysis.Test.Resources.Proprietary' from nuget 20150716.7 (20150716.5 and 20150716.6 are also broken) to 20150717.8, which contains the actually signed binary.

Nuget package
Roslyn sources depend on
Microsoft.CodeAnalysis.Test.Resources.Proprietary.1.1.0-beta1-20150716-05
which was not signed, so running tests was broken. I've uploaded a newer
package `07` to nuget.org that fixes the problem. This PR updates the
package references in Roslyn source to consume and build using the newer
package.

This

These were causing warnings in IDE due to #4192 and must be
been added by a bad package.

This is the start of our unit test assembly for our MSBuild assets.