Stop sorting unique item list when added item isn't equipped

[Wires77]

Description of the problem being solved:

Before, when you'd drag an item from the unique list to "All items", it would trigger a rebuild and thus a re-sort of the unique items. If this sort takes a long time but you're adding several items at once it can get quite frustrating. The rebuild isn't actually necessary so I removed it.

Steps taken to verify a working solution:

• Drag item to both items lists, no re-sort happens
• Drag item to item slot, re-sort happens
• Double click item and add to build that way, re-sort happens

Before screenshot:

After screenshot: