[feature] svg workflow

[yoshuawuyts]

We could maybs add a way to properly handle svg icons, e.g. as per https://www.sitepoint.com/a-working-svg-workflow-for-accessible-icons/

We'd then probably need to use something like:

• https://github.com/edenspiekermann/sprite.sh
• https://github.com/svg/svgo

Is this a good idea? I do think there's a need for this, as using svgs in projects is fairly common - anything we can do to help with that in a clean way is probably worth our efforts

[yoshuawuyts]

Goal is to make https://github.com/Kriesse/dat-icons not need a build step pretty much

[yoshuawuyts]

We now have --assets which partially helps with this

[yoshuawuyts]

So --assets is good - but I think for SVG specifically we should have a browserify transform that does it, that we can later extract from using a plugin or something so we can write to disk (similar to extract-css). Wouldn't mind having it be part of bankai if we ever get there