Add .editorconfig

Author: ribose-jeffreylau

.editorconfig

@@ -0,0 +1,23 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.{c,cpp,h{,.in}}]
+indent_style = space
+indent_size = 4
+
+[*.{cmake{,.in},json,sh,yml}]
+indent_style = space
+indent_size = 2
+
+[CMakeLists.txt]
+indent_style = space
+indent_size = 2
+
+[*.{adoc,md}]
+indent_style = space
+indent_size = 2