title: Deleted remote branches still listed in TortoiseGit
body: <p>I have noticed TortoiseGit seems to contain every feature branch I ever created, both in drop-downs for local branches AND remote, even though many of the remote branches were deleted after being merged into master.</p>
  
  <p>Is there a way in TortoiseGit to synhronise which branches are listed to those actually existing?</p>
  
  <p>And a slight tangent... in terms of Git itself is a local version of a branch considered totally decoupled from the remote? i.e. there is no reason why deleting the remote version <em>should</em> automatically mean the local one is deleted?</p>