Add editor config for 4 spaces instead of tab.
diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..e38e219
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,10 @@
+# editorconfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Default settings:
+# Use 4 spaces as indentation
+[*]
+indent_style = space
+indent_size = 4