Undo removes property fields?

[Yagira]

Changing a value on any of the fields and then using ctrl+z removes it from the editor. Happens on any part. Few examples:

1. model > change brightness > ctrl+z

[ERROR] addons/pac3-develop/lua/pac3/core/client/parts/model.lua:702: attempt to perform arithmetic on field 'Brightness' (a nil value)
  1. SetColor - addons/pac3-develop/lua/pac3/core/client/parts/model.lua:702
   2. unknown - addons/pac3-develop/lua/pac3/core/client/parts/model.lua:688
    3. undo - addons/pac3-develop/lua/pac3/editor/client/undo.lua:34
     4. ApplyUndo - addons/pac3-develop/lua/pac3/editor/client/undo.lua:162
      5. Undo - addons/pac3-develop/lua/pac3/editor/client/undo.lua:184
       6. thinkUndo - addons/pac3-develop/lua/pac3/editor/client/undo.lua:222
        7. v - addons/pac3-develop/lua/pac3/editor/client/undo.lua:387
         8. unknown - lua/includes/modules/hook.lua:84

2. model > change alpha > ctrl+z

[PAC3] failed to render Player [1][Yagira]:
addons/pac3-develop/lua/pac3/core/client/parts/model.lua:290: bad argument #1 to 'render_SetBlend' (number expected, got nil)
your pac3 outfit failed to render!

3. model > change tint color > ctrl+z

[PAC3] failed to render Player [1][Yagira]:
addons/pac3-develop/lua/pac3/core/client/parts/model.lua:193: attempt to perform arithmetic on field 'TintColor' (a nil value)
your pac3 outfit failed to render!

4. model > invert > size 4 > alpha 4 > ctrl+z Interesting results

[CapsAdmin]

I've redone the undo system. It should be working a lot better now but needs testing.