Fix bug #547753.

Fix bug #547753.

In class/Microsoft.Build.Engine/Microsoft.Build.BuildEngine:
	Fix bug #547753.
	* BatchingImplBase.cs (DumpBucket*): New. Useful for debugging.
	* Project.cs (Batch): New. Contains the perBatchItems and the
	commonItems for the batch.
	Use a stack of batches, instead of directly setting the current
	batch items.
	(PushBatch): New.
	(PopBatch): New.
	(SetBatchedItems): Make this private.
	(GlobalProperties.set): Re-evaluating the project is not required
	for this.
	* TargetBatchingImpl.cs: Use the new Push/PopBatch instead of directly
	setting the batches.
	* TaskBatchingImpl.cs: Likewise. Refactor slightly to PopBatch in
	finally block.
	* Target.cs (Build): Reset the current batch to nil before evaluating
	and building this target.

In class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks:
	* TaskBatchingTest.cs: Add new tests for batching.

git-svn-id: svn+ssh://mono-cvs.ximian.com/source/trunk/mcs@147050 e3ebcda4-bce8-0310-ba0a-eca2169e7518