add editorconfig.

Author: onmsr

.editorconfig

@@ -0,0 +1,15 @@
+# editorconfig
+root = true
+
+[*]
+end_of_line = LF
+charset = utf-8
+insert_final_newline = true
+
+[*.c]
+indent_style = space
+indent_size = 2
+
+[*.h]
+indent_style = space
+indent_size = 2