Added functionality of Multi-Trees --> an ability to store multiple values under the same key in the tree.
Merge branch 'voron' of https://github.com/myarichuk/raven.voron into voron

Conflicts:
	Voron.sln.DotSettings.user
	Voron/Trees/Tree.cs
Adding multi values to AllPages
Manual merge of pull request from Rob Lyndon
https://github.com/ayende/raven.voron/pull/4
Merge branch 'voron' of https://github.com/TMT-Rob/raven.voron into voron

Conflicts:
	Voron.sln.DotSettings.user
removing user file
Exposing issue with rebalancing