Some minor EMC mods

[Fred Proctor <frederick.proctor-at-nist.gov>]

EMC folks,

I put another EMC release on the FTP site, as Linux-19-Feb-1999.* This
is still for Red Hat 5.0, although a 5.2 port is almost finished. I
added the saving of G92 parameters to the rs274ngc.var file, just like
the G54-series of parameters is saved. You need to list the parameters
for the G92 axis offsets for them to be saved, so your rs274ngc.var file
should have this in it somewhere:

...
Only variables you put explicitly in here will be dumped out from
the interpreter.

Axes offsets for G92
5211    0.000000
5212    0.000000
5213    0.000000

Coordinate system for G54-- the default used at start
5221    0.000000
5222    0.000000
5223    0.000000
...

The values for 5211-5213 will be overwritten with whatever was active
when you did G92. If you clear them with G92.2 and then quit, they'll be
zero. If you don't want to save them, leave them out of the rs274ngc.var
file.

I also fixed a bug that prevented the offsets from showing up on the GUI
until you came out of estop, which was sort of annoying. This involved
changing the way command serial numbers were used with the IO controller
(shvio, mmio, ...) so if you notice any strange behavior with your IO
let me know. I didn't see anything when I ran my tests, but I don't have
a real machine.

On that note, I do have a Bridgeport knee mill that just arrived from
Bridgeport. I need to mount the motors, buy amps, and do electronics. I
hope this won't take too long and that I will shortly have a real
machine to test on. Our NIST machinists will be using this.

--Fred