add editorconfig policy

.editorconfig

+; http://editorconfig.org/
+
+[*]
+indent_style = space
+indent_size = 4
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[inc/{geshi,phpseclib}/**]
+; Use editor default (possible autodetection).
+indent_style =
+indent_size =
+trim_trailing_whitespace = false
+insert_final_newline = false