Use cursor for reads too
Partial fixes

Should switch writer to using cursor too, but current .NET wrapper crashes
Merge branch 'voron' of https://github.com/hyc/raven.voron into voron
Can now try to extend pure memory pager range (likely to fail, probably).
Small performance optimizations
Optimizing reads
Read optimization
More small read optimizations
Prefetch data on Windows 8 and up machines
Updating tests
Restoring write batch reading (although at a cost)
Merge branch 'voron' of https://github.com/ayende/raven.voron into voron
Merge branch 'voron' of https://github.com/ayende/raven.voron into voron

Conflicts:
	Voron/Impl/Backup/IncrementalBackup.cs
	Voron/Impl/Journal/JournalFile.cs
Small optimization
Moving compression to WAJ
Reverting, because it breaks the tests