Add editorconfig

Preserve options from master.

.editorconfig

@@ -0,0 +1,10 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = tab
+insert_final_newline = true
+max_line_length = 120
+tab_width = 2
+trim_trailing_whitespace = true