top: implement a new approach to forest view mode

top: implement a new approach to forest view mode

The TREE_RESCANS #define (formerly TREE_ONEPASS) has
been eliminated and the approach to forest view mode
redesigned.  The chance of dangling children has been
eliminated and overhead reduced.

We now order processes on start_time (non-display)
and are therefore immune to any pid, ppid or tgid
anomalies when pid values wrap.

The new algorithm also accommodates any distortions
caused by the 3.3 kernel 'hidepid' provisions --
something guaranteed to produce dangling children
under the former approach.

Related References:
commit a2086dfdf698f93de431349cf9a990fc5b95a768
commit cd608f462e587ee648f4bd0b798e77a52dd66c13
commit 41ed28aa5d2344e4838504a878a4db0afff8a6d8

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