Tweak the icons for the web font canvas discrepancies and rework line weight fidelity.

[jimmynotjim]

Using the updated canvas in #562, redraw the draft set of icons

[designlanguage]

@jimmynotjim -

Here are the revised SVGs: https://drive.google.com/open?id=1B6pawMHd3ku5WXXaVLwnmb90re-5kBAz

As mentioned in #562, sizing for the non-circled icons is larger and related to the baseline of Avenir Next. The icons in the circle are centered within it.

Here's what the latest sample icons look like:

[jimmynotjim]

Awesome. I'll get these into the web docs tomorrow