Re-order milestones and remove unwanted types

The administration for configuring Milestones is pretty frustrating.  In particular, the display order is so rigid.  It would be great to be able to re-order the milestones with the arrows and drag-and-drop that you have in other areas, instead of needing to go into each one and select a number.

Also, I don't use all of the pre-built milestone types and would like to be able to remove or hide some of them that the system doesn't allow to edit.  Please make this more flexible.