Add Clock set

[mdblack98]

rig_set_clock(rig,
Should work for these rigs on startup.
ic7100, ic7300, ic7600, ic7610, ic7700, ic7800, ic7851
UTC or local

Yaesu FT991A
Set Date: DT0yyyymmdd;
Set UTC Time: DT1HHMMSS;
Set Time Zone Offset: DT2[-]HHMM;

[mdblack98]

Icom rig routines could be normalize to an icom_set/get_clock with just the two added command bytes for the 1A05 command differences between rigs.
Need to check rest of Icom rigs
Yaesu rigs still needed

[mdblack98]

Implemented local and utc set options
So this works now
rigctl set_clock utc
rigctl set_clock local
b11f2e4

[mdblack98]

Argghh...strftime does not work properly on msys build
Rig command: \set_clock utc
194129Central Standard Time: rigctl_parse: cmd=(5c)
194129Central Standard Time: rigctl_parse: cmd=set_clock
195109Central Standard Time: rigctl_parse: vfo_opt=0
195109Central Standard Time: rigctl_parse.c(5226):rigctl_set_clock entered
195109Central Standard Time: rigctl_set_clock: utc time set = 195109Central Standard Time
195109Central Standard Time: rigctl_set_clock: n=1, 1951-01-00T-1:-1:-1.0.000+00
195109Central Standard Time: rigctl_set_clock: utc_offset=0
195109Central Standard Time: rigctl_set_clock: utc_offset=0
195109Central Standard Time: dummy_set_clock: 1951-01-00T-1:-1:-1.0.000+00