Fix memory leaks and enc string handling in DropItems.cpp

[3vcloud]

Was called ItemFilter.cpp, renamed for the drop tracking window.

• [x] PendingItems are alloc'd and then copied. The original item isn't freed.
• [x] Item stats should be grabbed from the mod struct, not from a decoded item info string.
• [x] Enc strings are processed one after another. This works but is a but messy, and theres no safety checks just in case the item is freed due the change in the above logic.