Querying history bounded when knowing the last changeset id wished
Merge branch 'fetching_only_needed_changesets'
Better handling big history by fetching changesets by lots

of 100 max (and creating commits in the same time)
before fetching another lot if needed....

& little refactoring
Merge back TfsHelper.PostVs2010.Common.cs in TfsHelper.Common.cs
Bring back all the TFS common code in TfsHelper.Common.cs (DRY!)
TfsPlugin is the same for all versions...
WrapperForWorkspace and WrapperForBranchObject could go in Wrappers.cs
Simplify a little more registry read for VS>=2012