[ale] How do you force a fixed resolution on Ubuntu 16.04

[ale_nospam at fayettedigital.com (Jim Lynch)]

Back in the bad old days, I could eventually put a xorg.conf file 
together that would make my monitor play.  Xorg.conf appears to be 
gone.  I have a situation where a box running 16.04 is connected to a 
monitor and a projector via a splitter.  Even when turned off, the 
projector somehow becomes the primary monitor.  Since the projector has 
better resolution the system at boot sets the resolution to a geometry 
that the monitor can't display.  Now the system looks like it's hung.  
We can disconnect the monitor cable temporarily to boot, but we'll 
eventually destroy the connectors that way.

I can't spend any money on the solution so the next best thing is to 
tell the computer to used a fixed resolution that the monitor can 
display.  The projector is happy with that setting too.

I can't seem to come up with the answer by searching, so I'd like some 
help. Xrandr might be the solution but I haven't figured out how to get 
it to effect the display before login.

Thanks,
Jim.