Merge: Clean primitive

Cleaning of binary operations on primitive data types:

* `lshift` and `rshift` are replaced by the usual `<<` and `>>`
* `bin_and` is replaced by `&`
* `bin_or` is replaced by `|`
* `bin_not` is replaced by `~`
* `bin_xor` is replaced by `^`

Note: Due to bootstrap issues, `<<` and `>>` are now FFI

Pull-Request: #1624
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>

diff --cc lib/markdown/markdown.nit
Simple merge