Upgrade browser to Elm 0.19

[mostlyobvious]

• https://github.com/avh4/elm-upgrade
• https://github.com/elm/compiler/blob/master/upgrade-docs/0.19.md
• https://github.com/rtfeldman/elm-spa-example/blob/master/src/Main.elm
• https://package.elm-lang.org/packages/elm/browser/latest/Browser#application

- NoRedInk/elm-json-decode-pipeline
  - [ ] Changes uses of Json.Decode.Pipeline.decode to Json.Decode.succeed
- elm/core
  - [ ] Replace uses of toString with String.fromInt, String.fromFloat, or Debug.toString as appropriate
- elm/html
  - [ ] If you used Html.program*, install elm/browser and switch to Browser.element or Browser.document
  - [ ] If you used Html.beginnerProgram, install elm/browser and switch Browser.sandbox
- elm/browser
  - [ ] Change code using Navigation.program* to use Browser.application
  - [ ] Use the Browser.Key passed to your init function in any calls to Browser.Navigation.pushUrl/replaceUrl/back/forward
- elm/url
  - [ ] Changes uses of Navigation.Location to Url.Url
  - [ ] Change code using UrlParser.* to use Url.Parser.*

[swistak35]

• NoRedInk/elm-json-decode-pipeline
  • [x] Changes uses of Json.Decode.Pipeline.decode to Json.Decode.succeed
• elm/core
  • [x] Replace uses of toString with String.fromInt, String.fromFloat, or Debug.toString as appropriate
• elm/html
  • [x] If you used Html.program*, install elm/browser and switch to Browser.element or Browser.document
  • [x] If you used Html.beginnerProgram, install elm/browser and switch Browser.sandbox
• elm/browser
  • [x] Change code using Navigation.program* to use Browser.application
  • [x] Use the Browser.Key passed to your init function in any calls to Browser.Navigation.pushUrl/replaceUrl/back/forward
• elm/url
  • [x] Changes uses of Navigation.Location to Url.Url
  • [x] Change code using UrlParser. to use Url.Parser.