Squashed 'Raven.Voron/' changes from 20de177..7addb35

7addb35 Making sure that we take all the trees snapshot at tx start
fcf7b67 added a test that exposes that snapshots are not isolated

git-subtree-dir: Raven.Voron
git-subtree-split: 7addb35bf65330574f5852d050c2d6136750ec88
Merge commit '1842b975cfa9630776961afde7526a67e579634c' into 2.5-voron

Conflicts:
	Raven.Voron/Voron.Tests/Voron.Tests.csproj
	Raven.Voron/Voron/Impl/Transaction.cs
	Raven.Voron/Voron/StorageEnvironment.cs
minor