First attempt at fixing some memory/speed issues with Version Control.

We are uselessly gathering DirectoryVersionInfo (and duplicating the items).

Tests on MD repo show that a minimum of 2300 VersionInfo's are created in current trunk. With this patch, the number is trimmed down to 340. This is a speed-up for loading. ( We also grabbed each directory multiple times: https://gist.github.com/Therzok/8bce3cf2b1f47b242b8a )

We also need to solve duplicate data that is done by DirectoryStatus and VersionInfo not being interdependent. We have VersionInfo for files at least twice now.