JSHint fixes

[shmert]

Using single-quotes

'use strict'

flag d3 as global var

[shmert]

Hi, just trying out the library, fixed some complaints that JSHint was having.

[dk8996]

I am cool with this. You commented out the following: //var FIXED_TIME_DOMAIN_MODE = 'fixed';

[dk8996]

@shmert take a look.