Chore/convert to typescript (#60)

* Convert to using TypeScript

Next.js v.9 allows converting an existing project to TS by simply renaming the files as TS files

* Fix type errors: Type 'string' is not assignable to type 'number'.

* Add mention about missing typings for javascript-time-ago

* Add GA_INITIALIZED to window

* Fix type error in feed transformers

* Model MembershipInfoForm state and props with TS

* Silence the typescript warning in MembershipInfoForm

* Add threshold to Fader props

* Fix Warning: Each child in a list should have a unique "key" prop.

Sponsors don't have ids – name is probably unique and can be used as a key

* Allow key as prop for SponsorLink

* Add type of the props for SponsorLink

data/projects.ts

@@ -0,0 +1,28 @@
+const projects = [
+  {
+    title: "RE:DOM",
+    description:
+      "Tiny (2 KB) turboboosted JavaScript library for creating user interfaces. Develop web apps with 100 % JavaScript and web standards.",
+    url: "https://redom.js.org",
+    image: "/static/images/redom.svg",
+  },
+  {
+    title: "Code::Stats",
+    description: "Code::Stats is a free stats tracking service for programmers",
+    url: "https://codestats.net/",
+    image: "/static/images/codestats.png",
+  },
+  {
+    title: "Reactabular",
+    description: "A framework for building the React table you need",
+    url: "https://reactabular.js.org/",
+    image: "/static/images/reactabular.png",
+  },
+  {
+    title: "Avain.app",
+    description: "Secure one-time password manager (PWA + Web Crypto)",
+    url: "https://avain.app",
+    image: "/static/images/avain.svg",
+  },
+];
+export default projects;