[dpkdir] restart VFS only for Map_Free() and Map_LoadFile(), refresh others

[dpkdir] restart VFS only for Map_Free() and Map_LoadFile(), refresh others

Since there is no map file observer anymore for that stuff,
we Restart or Refresh it explicitely when needed.

- Opening map or New map needs Restarting VFS.
- Saving map or Renaming map (Save as) needs Refreshing VFS.

The Refresh also triggers the Texture browser.

A previous fix for #105 was done Refreshing VFS instead of Restarting it
but it was not perfect, for example map opening behavior is better with
VFS restart, and map saving needs to refresh the VFS and the texture
browser but not restart (that was the earlier fault). So, it's clearly
not a good idea to trigger either Refresh or Restart on any map event
since the behavior differs according to the event.

If one day one plugin wants to act on VFS on map event, it must refresh or
restart VFS according to what the plugin does. It does not make sense to
trigger the same task for different events.