Add arithmetic shift, use logic shift in current right shift (#1670)

* Add arithmetic shift, use logic shift in current

* State that the MSBs will be cleared to zero in logic right shift

docs/scarpet/language/Operators.md

@@ -308,7 +308,10 @@ only take integer values, so if the input has a decimal part, it will be discard
 	tend to -1.
  - `bitwise_shift_left(num, amount)` -> Shifts all the bits of the first number `amount` spots to the left. Note that shifting more
 	than 63 positions will result in a 0 (cos you shift out all the bits of the number)
- - `bitwise_shift_right(num, amount)` -> Shifts all the bits of the first number `amount` spots to the right. Like with the above,
+ - `bitwise_shift_right(num, amount)` -> Shifts all the bits of the first number `amount` spots to the right logically. That is, the 
+    `amount` most significant bits will always be set to 0. Like with the above, shifting more than 63 bits results in a 0.
+ - `bitwise_arithmetic_shift_right(num, amount)` -> Shifts all the bits of the first number `amount` spots to the right arithmetically.
+    That is, if the most significant (sign) bit is a 1, it'll propagate the one to the `amount` most significant bits. Like with the above,
 	shifting more than 63 bits results in a 0.
  - `bitwise_roll_left(num, amount)` -> Rolls the bits of the first number `amount` bits to the left. This is basically where you
 	shift out the first `amount` bits and then add them on at the back, essentially 'rolling' the number. Note that unlike with