Squashed 'Raven.Voron/' changes from d5f9e6e..830aa87

830aa87 added ReadResult
63a055a RavenDB-1331 Voron - Avoid saving trees that were not modified
fe75e26 Make sure we write the sub tree record to the right location
1e7b294 Properly account for root page in sub trees
552c392 RavenDB-1330 Voron - support deleting trees
e97dcb3 Slightly better Slice.ToString()
85654fe Allow snapshots for multi reads
ae4f64f Minor refactoring
44a4cc8 Now supporting iterators that can go backward
7927534 added a comment to unclear code in batch tests that was forcing to build one batch group from incoming batches

git-subtree-dir: Raven.Voron
git-subtree-split: 830aa8791a61547ab8f108316edab955271a6188
Merge commit '18c3002ddb5e457a15b05b44da36da614f989298' into 2.5-voron

Conflicts:
	Raven.Voron/Voron.Tests/Storage/Batches.cs
	Raven.Voron/Voron.Tests/Storage/Snapshots.cs
	Raven.Voron/Voron.Tests/Voron.Tests.csproj
	Raven.Voron/Voron/Impl/SnapshotReader.cs
	Raven.Voron/Voron/Impl/Transaction.cs
	Raven.Voron/Voron/Impl/WriteBatch.cs
	Raven.Voron/Voron/StorageEnvironment.cs
	Raven.Voron/Voron/Trees/Tree.cs
	Raven.Voron/Voron/Voron.csproj
merge fixes
Squashed 'Raven.Voron/' changes from 830aa87..b07c975

b07c975 Merge branch 'voron' of https://github.com/ayende/raven.voron into voron
4c00f14 added multiadd/delete to writebatch
42e12af Minor
c437595 Merge branch 'voron' of https://github.com/ayende/raven.voron into voron
3bb7f2b Making sure that we can modify tree existence in a transactional manner.

git-subtree-dir: Raven.Voron
git-subtree-split: b07c97574cb57239c7ef3ecf511cadfbca481fea
Merge commit '545b5f3cb824c5616a8c4ec9c409d0b90cb15023' into 2.5-voron

Conflicts:
	Raven.Voron/Voron.Tests/Bugs/EmptyTree.cs
	Raven.Voron/Voron.Tests/Trees/MultipleTrees.cs
	Raven.Voron/Voron/Impl/SnapshotReader.cs
	Raven.Voron/Voron/Impl/Transaction.cs
	Raven.Voron/Voron/Impl/TransactionMergingWriter.cs
	Raven.Voron/Voron/Impl/WriteBatch.cs
	Raven.Voron/Voron/StorageEnvironment.cs
started working on IndexingStorageActions