Elm v0.19

[Libbum]

Closes #95 once everything is sorted out.

Need a few packages to be updated:

• https://github.com/elm-community/elm-time -> elm/time
• https://github.com/elm-community/maybe-extra -> PR sent
• https://github.com/elm-lang/navigation -> elm/browser
• https://github.com/ktonon/elm-crypto -> dep on elm-word -> PR sent there first
• https://github.com/lukewestby/http-builder -> lukewestby/elm-http-builder 6.0.0
• https://github.com/pukkamustard/elm-identicon -> waiting on elm/color
• https://github.com/rtfeldman/elm-css -> WIP from developer
• https://github.com/rtfeldman/elm-css-helpers -> assume as above
• https://github.com/scottcorgan/elm-css-normalize -> drop to fulfil Remove normalise.css #89

Or we can drop some support / change our implementation. For example we already use a very old elm-css, so we can dump that for the time being (and get #81 functioning later on).
Additionally elm-time is now replaced by something new I think (update: elm/time). navigation I'm pretty sure we take next to nothing out of it etc. (update: navigation is now part of elm/browser, which has some cool stuff in it)

Additionally: viewport etc dropped, so the #70 stuff should be golden now.

[Libbum]

Started with elm-identicon. Looks like it's probably a few days away from actually being able to do anything productive here. The core got seemingly too large so a number of things have been separated out. The first issue we hit here is the need for Color, which is now here but not on package.

[Libbum]

Have put in PRs for elm-word (a dependency of elm-crypto) and maybe-extra. The latter should merge quickly, but the author of word/crypto hasn't been around github for some time. Not sure what horizon to expect there.

[Libbum]

Just a note on the upgrade: There are a few places where we need to interop with JS now. So look into actually using TypeScript here instead to keep the system as coupled as possible:

https://github.com/dillonkearns/talks/tree/master/types-without-borders

[Libbum]

The markdown portion was one of the stickiest places (along with KaTeX inclusion). It's possible that the work on elm-markup is stable enough now to use for this portion. A good writeup on the current version.