Replace the `stream' in variable name `in_stream' or `input_stream' to `channel'
Add the vertical bar to first case in pattern matching in block match...with
Remove the use of variable dq

The variable `dq` is used because the ocaml-mode from OCaml 3.12.0
distribution can't recognize the double quote mark correctly.
Remove the definition and apply of function `is_double_quote'
The change of the if...then identation style
Add the first primitive procedure, the plus function.