top: make command line switch parsing even more robust

top: make command line switch parsing even more robust

This program has always tried to maintain an extermely
robust command line parsing procedure, far more robust
that what's available with the getopt stuff. But, with
the introduction of our first numeric switch it should
have been made even more robust than, in fact, it was.

This commit will now accomplish such a desirable goal.

Reference(s):
. added '1' command line switch
commit 5e708c5db71c2c765f5926fbc771471fa69c0ea6

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