Create search service to more easily use prefabs

[decaprime]

.search items was a prototypical implementation that seems to be popular. I want to expand this into a more robust service that handles items, units, and buffs.

The biggest feedback (and personal gripe) is that you still have to type the prefab guid or name, without a client mod to make selecting easier, having a shorter id to use would be great. The two options I see are:

• alternative encoding of int hash: 2^32 is still 36^7 to represent in alternative base. We could reencode as there's not that many of them, but they're unlikely to be stable through patches
• temporary index with numbered results: the search results would say #1 -2713827328 Dagger_Special_Thing and an in memory cache could be created per type/user to store the actual prefab, and the user could call .g #1 to refer to the last item search result.