Favicon experiements

I am a programmer, not an artist, but here are some experiential icons
I whipped up.

They are only visible in the settings drawer when you add
`?experiments=true` to your site’s URL. Clicking on the icon will
change the favicon in the tab at the top of your browser.

For example you can see them at http://localhost:1337/?experiments=true
Favicon experiments

I am a programmer, not an artist, but here are some experiential icons
I whipped up.

They are only visible in the settings drawer when you add
`?experiments=true` to your site’s URL. Clicking on the icon will
change the favicon in the tab at the top of your browser.

For example you can see them at http://localhost:1337/?experiments=true
Favicon Experiments (added drop2a.png)

I am a programmer, not an artist, but here are some experiential icons
I whipped up.

They are only visible in the settings drawer when you add
`?experiments=true` to your site’s URL. Clicking on the icon will
change the favicon in the tab at the top of your browser.

For example you can see them at http://localhost:1337/?experiments=true
Favicon Experiments (2 more artist's icons)

I have included two more of the round head treatment that we haven’t
tried before.
Toolbar Logo experiments

I added the two B&W logos. I like the primarily white one best.
Fix: restored mg/dL chart "tickValues"

The values on the right hand side were missing when on mg/dL.
Merge pull request #11 from nightscout/rebase/settings

Rebase/settings