top: provide the means to adjust scaled summary memory

Earlier this year, the switch from KiB to Mib as shown
in top's summary area was postponed to those occasions
when KiB exceeded 8 digits. In hindsight that may have
moved top in the wrong direction, given the difficulty
of digesting such large numbers of digits at a glance.

This commit adds a new 'E' interactive command used to
cycle the displayed memory amounts ranging from KiB to
TiB. Thus, users can choose the radix they wish shown.

p.s. and it will be rcfile preserved for any restarts!

(now that we know a '.' + 2 spaces is squeezed to one)
(everything's perfectly justified, but it's just luck)

Reference(s):
http://www.freelists.org/post/procps/top-regression-reports

commit 95f2201730
Author: James Cloos <cloos@jhcloos.com>
Date:   Mon Feb 6 00:00:00 2012 -0500

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

top/top.h

@@ -336,6 +336,7 @@ typedef struct RCF_t {
    int    win_index;            // Curwin, as index
    RCW_t  win [GROUPSMAX];      // a 'WIN_t.rc' for each window
    int    fixed_widest;         // 'X' - wider non-scalable col addition
+   int    summ_mscale;          // 'E' - scaling of summary memory values
 } RCF_t;
 
         /* This structure stores configurable information for each window.