This is the regular batch update for outdated dependencies.

It includes the long awaited React version 16.8.0 (1) that finally
brings the stable Hooks API (2) as well as great performance
improvements and bug fixes!

Updated Jest's configuration since version `>=24.0.0` deprecated
`setupTestFrameworkScriptFile` in favor of the new
`setupFilesAfterEnv` (3) option.

The ESLint plugin `eslint-plugin-react` includes a lot of improvements
and bug fixes regarding the parsing of code structures for better prop
validation and display name detection. This resulted in the requirement
to implement currently missing prop types in various SFC and class
components in the project as well globally (temporally) disabling the
`react/display-name` rule to prevent warning message noise.

Gatsby and all plugins have been updated to the latest versions to
include the latest improvements and bug fixes. `gatsby-plugin manifest`
now sets the `legacy` option to `true` by default (4) to include Apple
touch icons since the assumption was wrong that iOS supports the icons
from the web manifest.

As of version 3.3 the "Inter UI" font typeface has been renamed and is
now "Inter" (5), without the "UI" part. This change has been ported to
the used inter-ui (6) package. The import has been adjusted to match the
renamed `inter.css` main file and all references to the "Inter UI" name
have been adjusted by removing "UI".

Prettier version 1.16.0 (7) comes with support for React Hooks and
features for TypeScript and HTML as well as many other improvements and
bug fixes.

React Pose includes an important fix that also animates all other
children when items are moving (8) when using the `PoseGroup` component.

>>>>>> Production Dependencies

- gatsby `2.0.75` -> `2.0.117`
- gatsby-plugin-canonical-urls `2.0.8` -> `2.0.10`
- gatsby-plugin-catch-links `2.0.9` -> `2.0.10`
- gatsby-plugin-google-gtag `1.0.8` -> `1.0.13`
- gatsby-plugin-manifest `2.0.12` -> `2.0.17`
- gatsby-plugin-netlify `2.0.6` -> `2.0.9`
- gatsby-plugin-no-sourcemaps `2.0.1` -> `2.0.2`
- gatsby-plugin-offline `2.0.20` -> `2.0.23`
- gatsby-plugin-react-helmet `3.0.5` -> `3.0.6`
- gatsby-plugin-remove-trailing-slashes `2.0.6` -> `2.0.7`
- gatsby-plugin-robots-txt `1.3.0` -> `1.4.0`
- gatsby-plugin-sitemap `2.0.3` -> `2.0.5`
- gatsby-plugin-styled-components `3.0.4` -> `3.0.5`
- gatsby-source-filesystem `2.0.12` -> `2.0.20`
- gatsby-transformer-yaml `2.1.6` -> `2.1.8`
- inter-ui `3.1.0` -> `3.3.2`
- polished `2.3.1` -> `2.3.3`
- react `16.7.0` -> `16.8.1`
- react-dom `16.7.0` -> `16.8.1`
- react-pose `4.0.4` -> `4.0.6`
- typeface-source-code-pro `0.0.54` -> `0.0.71`

>>>>>> Development Dependencies

- @babel/plugin-proposal-class-properties `7.2.3` -> `7.3.0`
- babel-jest `23.6.0` -> `24.1.0`
- babel-plugin-transform-react-remove-prop-types `0.4.21` -> `0.4.24`
- babel-preset-gatsby `0.1.6` -> `0.1.7`
- eslint `5.11.0` -> `5.13.0`
- eslint-plugin-import `2.14.0` -> `2.16.0`
- eslint-plugin-jsx-a11y `6.1.2` -> `6.2.1`
- eslint-plugin-prettier `3.0.0` -> `3.0.1`
- eslint-plugin-react `7.11.1` -> `7.12.4`
- husky `1.2.1` -> `1.3.1`
- jest `23.6.0` -> `24.1.0`
- jest-dom `3.0.0` -> `3.0.2`
- jest-junit `5.2.0` -> `6.2.1`
- lint-staged `8.1.0` -> `8.1.3`
- prettier `1.15.3` -> `1.16.4`
- react-testing-library `5.4.2` -> `5.5.3`

References:
  (1) https://reactjs.org/blog/2019/02/06/react-v16.8.0.html
  (2) https://reactjs.org/docs/hooks-intro.html
  (3) jestjs/jest#7119
  (4) gatsbyjs/gatsby#11203
  (5) https://github.com/rsms/inter/releases/tag/v3.3
  (6) https://www.npmjs.com/package/inter-ui
  (7) https://prettier.io/blog/2019/01/20/1.16.0.html
  (8) Popmotion/popmotion#682

Resolves GH-120