SPATIAL index support

[NiciusB]

I'm using POINT columns, and while this package apparently isn't very tested on those, it's worked great for me so far. However I encountered a problem while trying to create SPATIAL indexes, since the SPATIAL type was being ignored, and they were being created as normal indexes.

A quick patch fixed it: NiciusB@6c26e8d

But since the solution is hacky, and there's probably a cleaner way to handle indicesType, I won't create a pull request. I'll be using my github repo instead of this npm package until a solution is shipped, so I'd be great if this was eventually fixed.

Thanks!