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.1

@@ -421,14 +421,14 @@ kernel versions are shown first.
 .SS 2c. MEMORY Usage
 .\" ----------------------------------------------------------------------
 This portion consists of two lines which may express values in kibibytes (KiB),
-mebibytes (MiB) or gibibytes (GiB) depending on the amount of currently
-installed \*(MP.
+mebibytes (MiB) or gibibytes (GiB) depending on the scaling factor enforced
+with the 'E' \*(CI.
 
 Line 1 reflects \*(MP, classified as:
-    total, used, free, buffers
+    total, used, free and buffers
 
-Line 2 reflects \*(MV, classified as:
-    total, used, free, cached
+Line 2 reflects mostly \*(MV, classified as:
+    total, used, free and cached (which is \*(MP)
 
 .\" ----------------------------------------------------------------------
 .SH 3. FIELDS / Columns
@@ -832,7 +832,8 @@ depending on the context in which they are issued.
 
 .Bd -literal
   4a.\fI Global-Commands \fR
-        <Ent/Sp> ?, =, A, B, d, g, h, H, I, k, q, r, s, W, X, Y, Z
+        <Ent/Sp> ?, =,
+        A, B, d, E, g, h, H, I, k, q, r, s, W, X, Y, Z
   4b.\fI Summary-Area-Commands \fR
         C, l, t, 1, m
   4c.\fI Task-Area-Commands \fR
@@ -927,6 +928,16 @@ so set it with care.
 If at any time you wish to know the current delay time, simply ask for
 help and view the system summary on the second line.
 
+.TP 7
+\ \ \'\fBE\fR\' :\fIExtend-Memory-Scale\fR in Summary Area
+With this command you can cycle through the available \*(SA memory scaling
+which ranges from KiB (kibibytes or 1,024 bytes) through TiB (tebibytes or
+1,099,511,627,776 bytes).
+
+If you see a '+' between a displayed number and the following label, it
+means that \*(We was forced to truncate some portion of that number.
+By raising the scaling factor, such truncation can usually be avoided.
+
 .TP 7
 \ \ \'\fBg\fR\' :\fIChoose-Another-Window/Field-Group \fR
 You will be prompted to enter a number between 1 and 4 designating the