Indents too long

[xhevahir]

I've noticed that hitting tab results in a very long indentation--twice as long as expected, to be exact. (I.e., eight spaces rather than four.) I'm having a hard time figuring out how to change this. I thought maybe this is a more general setting in Vim rather than a Nim-specific one, but I've only noticed it when writing Nim.

Sorry, just discovered this was already noted in Issue #34.