refactor diagnostic service to prepare prototype work

Eek!  Remove unused type parameter introduced by my last commit...

Display "ref" and "out" modifiers on parameter types as in the old Call Stack Window implementation.

Add skipped test for #399

Add test for string concatenation operator with mutable value types

NuGet authoring for Microsoft.DiaSymReader

VB: Remove unnecessary check for ModuleBuilderOpt during lowering phase

Exclude mscorlib from Emit test conflict checking

In the emit tests we currently check every module to see if we're
emitting an assembly with a name we've already seen. PeVerify
requires that we create a new AppDomain for every conflict we find.
However, mscorlib will always produce a conflict, so this ignores
mscorlib when checking for a conflict and doesn't create a new
AppDomain if it is found during emit.

Use AssertTheseEmitDiagnostics instead of compilation.VerifyEmitDiagnostics to keep the orignal baseline form.

do not load all diagnostic analyzers in host analyzer references

we can end up load analyzers for a language that does not even exist in current solution.

Display "ref" and "out" modifiers on parameter types as in the old Call Stack Window implementation.

Also add a simple tests for params/array parameters...

properly handle VB Global namespace in DeclaredSymbolInfo

Add *.wrn to .gitignore

Add skipped test for https://github.com/dotnet/roslyn/issues/320

Fix SimpleDiagnostic GetHashCode is more specific than Equals

we can end up load analyzers for a language that does not even exist in current solution.

These checks were required for some VB tests, not for product code.
By updating VB tests, we can remove them and simplify the lowering phase.

Add skipped test for https://github.com/dotnet/roslyn/issues/320: Possible bug in Batch Fixer merge algorithm.

Create new projects for System.Runtime.Analyzers

fix #314 - remove dead code

It is apparently possible for a test to exit with an error code, produce
no HTML file and no output.  In that case the call to Aggregate was
failing with an exception.  Change it to use ToArray +
File.WriteAllLines.

This won't fix the underlying problem but will at least identify the
test that is failing.

Substitute generic type arguments for generic frames in the Call Stack Window.