MacBook is sleeping despite being set to "never" sleep
It's working properly again.  Got  up this morning and computer remained awake for the entire night.

The only thing I did since last failure:  I deleted the following file in the root Library, and re-entered my Energy Savings preferences.

/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist


The Terminal now reports this for pmset -g.  Note the difference on the first two lines.  I guess the original settings were somehow corrupted.

MacBook:~ myusername$ pmset -g
Active Profiles:
Battery Power   -1
AC Power        -1*
Currently in use:
 lidwake    1
 autorestart    0
 halfdim    1
 sms        1
 hibernatefile  /var/vm/sleepimage
 disksleep  0
 sleep      0
 hibernatemode  3
 ttyskeepawake  1
 displaysleep   15
 acwake     0
 womp       0