Introduce https://editorconfig.org/ file

Some editors support it out of the box, others need a plugin like https://marketplace.visualstudio.com/items?itemName=EditorConfig.EditorConfig

.editorconfig

@@ -0,0 +1,33 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+# Matches multiple files with brace expansion notation
+# Set default charset
+[*.{js,py}]
+charset = utf-8
+
+# 4 space indentation
+[*.py]
+indent_style = space
+indent_size = 4
+
+# Tab indentation (no size specified)
+[Makefile]
+indent_style = space
+
+# Indentation override for all JS under lib directory
+[lib/**.js]
+indent_style = space
+indent_size = 2
+
+# Matches the exact files either package.json or .travis.yml
+[{package.json,.travis.yml}]
+indent_style = space
+indent_size = 2