Implement AssignProjectConfiguration task.

Implement AssignProjectConfiguration task.

In class/Microsoft.Build.Tasks:

	* Microsoft.Build.Tasks_test.dll.sources: Added
	AssignProjectConfigurationTest.cs .

	* Microsoft.Build.Tasks.dll.sources: Added
In class/Microsoft.Build.Tasks/Microsoft.Build.Tasks:

	* AssignProjectConfiguration.cs (Execute): Implement.

In class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks:

	* AssignProjectConfigurationTest.cs: New.

In tools/xbuild:

	* xbuild/Microsoft.Common.targets (AssignProjectConfigurations): New.
	(ResolveProjectReferences): Add dependency on AssignProjectConfigurations
	target. Also, set the config and platform properties for the msbuild task
	being invoked.
	* xbuild/Microsoft.Common.tasks: Add AssignProjectConfiguration .

In tools/xbuild/tests:

	* standalone/Project01: Change config mappings a bit to mix them up,
	like Debug->Release etc. Update .proj file and final-outputs.txt.

svn path=/trunk/mcs/; revision=138461