CSHARP-943: Split large batches correctly when InsertBatch is being emulated using write commands.
CSHARP-943: Added more unit tests.
removed pre-release note in release notes.
Bumping version post release.
Merge branch 'master' of https://github.com/mongodb/mongo-csharp-driver

Conflicts:
	MongoDB.DriverUnitTests/MongoCollectionTests.cs
	MongoDB.DriverUnitTests/Operations/BulkWriteOperationTests.cs
	MongoDB.DriverUnitTests/Operations/DeleteCommandEmulatorTests.cs
	Release Notes/Release Notes v1.9.md
	build.ps1