Add support to underscored tables

[GabrielNexT]

Hi guys, I was developing a small project and I found a bug.

Basically when we create an index with a table with the underscored property, we get an SQL error. As it seemed like a simple bug, I decided to explore to try to find a solution.

The idea I had is very simple, if you have the property, let's convert the name of all the fields of all the indexes to snake case and that's what I did, apparently it solves the problem.

This is my first contribution to an open source project, please be patient :)

Other people reported this bug in this issue #725

[GalvinGao]

Any update on this from the maintainers with push access? This looks like a very nice fix to merge into the upstream :D