simplify code contributions + reviews by fully automating the dev setup with Gitpod. (#824)

.gitpod.Dockerfile

@@ -0,0 +1,4 @@
+FROM gitpod/workspace-full
+
+RUN sudo apt-get update \ 
+    && sudo apt install ffmpeg -yq

.gitpod.yml

@@ -0,0 +1,10 @@
+image: 
+  file: .gitpod.Dockerfile
+tasks:
+  - init: yarn && gp sync-done boot
+  - before: cd gulp
+    init: gp sync-await boot && yarn
+    command: yarn gulp 
+ports: 
+  - port: 3005
+    onOpen: open-preview

README.md

@@ -31,6 +31,16 @@ Your goal is to produce shapes by cutting, rotating, merging and painting parts
 
 **Notice**: This will produce a debug build with several debugging flags enabled. If you want to disable them, modify [`src/js/core/config.js`](src/js/core/config.js).
 
+## Build Online with one-click setup
+
+You can use [Gitpod](https://www.gitpod.io/) (an Online Open Source VS Code-like IDE which is free for Open Source) for working on issues and making PRs to this project. With a single click it will start a workspace and automatically:
+
+- clone the `shapez.io` repo.
+- install all of the dependencies.
+- start `gulp` in `gulp/` directory.
+
+[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)
+
 ## Helping translate
 
 Please checkout the [Translations readme](translations/).