sqimap_msgs_list_copy now does what you'd expect it to.

sqimap_msgs_list_copy now does what you'd expect it to.
sqimap_msgs_list_move does what _copy USED to do.
Only one reference to that function needed to be changed in the core code.
No core plugins use it.

git-svn-id: https://svn.code.sf.net/p/squirrelmail/code/trunk/squirrelmail@5502 7612ce4b-ef26-0410-bec9-ea0150e637f0