top: trade just 1 'Ctrl' bottom window key association

I grew tired of inadvertently causing a premature exit
from top when all I wanted was to review some process'
environment variables. That 'V' key was just too close
to the 'C' key so the '^V' attempt became one of '^C'.

Well, not any more. Should a user wish to see a task's
environment, it will now require the '^N' combination.

[ it also now places G/U & N/K on a similar diagonal ]

Along the way, lower case Ctrl key combinations on the
help screen were all changed into upper case versions.

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

top/top.h

@@ -173,10 +173,10 @@ char *strcasestr(const char *haystack, const char *needle);
 #define kbd_CtrlE  '\005'
 #define kbd_CtrlG  '\007'
 #define kbd_CtrlK  '\013'
+#define kbd_CtrlN  '\016'
 #define kbd_CtrlO  '\017'
 #define kbd_CtrlR  '\022'
 #define kbd_CtrlU  '\025'
-#define kbd_CtrlV  '\026'
 
         /* Special value in Pseudo_row to force an additional procs refresh
            -- used at startup and for task/thread mode transitions */