Add CONFigure:FANx:HYSteresis command (#2)

[Zitt]

Allows user to change the hysteresis of a given fan to limit the amount of INFO lines sent to LOG and/or SYSLOG.

[tjko]

Thanks, looks good. I'll just make couple tweaks to keep commands consistent with existing commands (and to behave like other SCPI commands).

[Zitt]

@tjko I made even more changes in my fork:
135afb4
but I wasn't completely happy with the implementation.

I wanted there to be a HYST sub command (IE see line 2751 in command.c).
but after spending hours trying to make it work; I realized that you can't have CONF:FANx:HYS:PWM?
because the code isn't structured to "save" the fan index in
run_cmd()
function. The code is only able to "look back" and previous cmd and not prev_cmd-1 for the index.
I couldn't make it work.

As a result; I just flattened the PWM and TACHO hysteresis commands into
CONFigure:FANx:HYS_Tacho
CONFigure:FANx:HYS_Pwm

IF you'd like me to try a pull request with my changes; please let me know.

[tjko]

@Zitt, I noticed same when looking the pull request :)

Current "prev_cmd" pointer was a "temporary" hack, that I never got around to fix it seems.
I'll see if I can make change to expose the full command "stack" to the command functions in case they're interested other than the previous command in the chain...

[Zitt]

Looks like your current commit #108 has the updated changes from my commit.