Made a library factory so we can add additional libraries at runtime.

Made the scroll bar for the library stay on screen.
Made the item insertion go in the right place
Refactoring

PrintLibrary/Provider/LibraryProviderFileSystem.cs

@@ -99,11 +99,11 @@ namespace MatterHackers.MatterControl.PrintLibrary.Provider
 			}
 		}
 
-		public override string Key
+		public override string ProviderTypeKey
 		{
 			get
 			{
-				return "LibraryProvider_" + key.ToString();
+				return "LibraryProvider_" + key.ToString() + "_Key";
 			}
 		}