top: kill/nice provide for a default pid

top: kill/nice provide for a default pid

As an aid to the above 2 commands, and as a prelude to
an upcoming 'inspect other output' capability, the act
of selecting a process for either has been simplified.

Positioning a task as the first one displayed, via the
up/down arrow keys, will now establish it as a default
selection for the appropriate command.  Thus, that pid
will then be incorporated in a subsequent input prompt.

Signed-off-by: Jim Warner <james.warner@comcast.net>