Add basic EditorConfig

EditorConfig simplifies setting up an IDE / editor.
It is supported by many tools like Vim, IntelliJ or Emacs.
It doesn't support all options which are set in GoogleFormat.xml,
but is a good base for tools other than Eclipse.

Change-Id: I9777f0410f8ba3e39b6df046903947ac15ad9527

.editorconfig

@@ -0,0 +1,11 @@
+# http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = space
+indent_size = 2