Feature: null layout option for sprite mode

[growdigital]

I'm pulling in the sprite.svg using Ajax.

Would be good to have the option to set layout to null, as I'm referencing the individual svg icons by their ID, so I don't need coordinates, which I'm having to strip out from the generated file.

layout variable is in here: https://github.com/shakyShane/gulp-svg-sprites/blob/master/index.js

[growdigital]

FWIW, I hacked this file:
/gulp-svg-sprites/node_modules/svg-sprite-data/lib/svg-sprite.js

with this:

        // No sprite arrangement
        case 'none':
            positionX = null;
            positionY = null;
            break;

And it seems to work, which is kind of handy. I don't know that JavaScript very well though, so could be horribly broken…

[growdigital]

Have created pull request for this file:

https://github.com/shakyShane/svg-sprite-data/blob/master/lib/svg-sprite.js