[Bug-apl] )COPY should not copy ⎕PW

[Blake McBride]

According to the IBM APL2 Programming Language Reference (page 423), the
)COPY command should not copy ⎕PW.  The manual states:  "The only system
objects that can be copied are ⎕CT, ⎕FC, ⎕IO, ⎕LX, ⎕PP, ⎕PR, and ⎕RL.

Current GNU APL:

      )CLEAR
CLEAR WS
      ⎕PW←80
      )save ws1
2014-07-01  20:57:00 (GMT-5)
      ⎕PW←132
      )COPY ws1
SAVED 2014-07-02 -4:57:00 (GMT-5)
      ⎕PW
80