Removed setr command. It was never meant to be available.

- The command implementation is kept, with an internal-use prefix, to be
  used by direct assignment commands.

Signed-off-by: Haru <haru@dotalux.com>
Marked command jump_zero as deprecated.

- Added prefixed version for internal use.

Signed-off-by: Haru <haru@dotalux.com>