Changes to handle OST 2013 files

With Outlook 2013, Microsoft changed the format used for OST (and NST) files to account for larger file sizes.

My starting point was this blog entry called "OST 2013 File Format - The Missing Documentation".

In addition to the changes listed there, I found the following differences:

1. It is possible for a folder to have a non-zero content count but not have an associated Contents Table. This was observed with the "Reminders", To-Do Search", and "Contact Search" folders under the "Finder" folder. (3f199b8a45e422fba2eeea2515e92d88b2f3cf2e)
2. The Message Store for OST files does not include the IpmSubTreeEntryId, so the root folder needs to be found using a different mechanism - by searching for the NBTEntry which has itself as its parent.