Standardize time metadata

[samsrabin]

Description of changes

Standardizes a dimension name of output variable time_bounds, as well as attributes for that plus mcdate, mcsec, mdcur, and mscur.

Specific notes

Contributors other than yourself: @phillips-ad, @ekluzek

MOSART Issues Fixed:

• Fixes Modify naming and attributes of time variables on history files to be consistent with other CESM components #53
• Contributes to CTSM issue Modify naming and attributes of time variables on history files to be consistent with other CESM components CTSM#1693 and CTSM PR Standardize time metadata (we will mark this as the release tag for ctsm5.3) CTSM#2052.

Are answers expected to change (and if so in what way)? No.

Any User Interface Changes (namelist or namelist defaults changes)? No.

Testing performed

New metadata in a history file from a short test:

netcdf standardize-time-metadata.mosart.h0.1850-01-06-00000 {
dimensions:
	...
	nbnd = 2 ;
	...
variables:
	...
	int mcdate(time) ;
		...
		mcdate:calendar = "noleap" ;
	int mcsec(time) ;
		...
		mcsec:calendar = "noleap" ;
	int mdcur(time) ;
		...
		mdcur:calendar = "noleap" ;
	int mscur(time) ;
		...
		mscur:calendar = "noleap" ;
	...
	double time_bounds(time, nbnd) ;
		time_bounds:long_name = "time interval endpoints" ;
		time_bounds:units = "days since 1850-01-01 00:00:00" ;
		time_bounds:calendar = "noleap" ;

An arbitrarily-chosen CTSM test with MOSART, SMS_D_Ld3.f10_f10_mg37.I2000Clm50BgcCru.cheyenne_gnu.clm-default, passed bit-for-bit against tag ctsm5.1.dev130, despite the changed metadata.

• Reminder to update ChangeLog

[mvertens]

@slevis-lmwg @jedwards4b - I think this should be merged at this point. I can also bring these changes into #76 once it is merged.

[slevis-lmwg]

@slevis-lmwg @jedwards4b - I think this should be merged at this point. I can also bring these changes into #76 once it is merged.

Thank you @mvertens.
The merge order that @ekluzek and I agreed to is here:
https://github.com/ESCOMP/CTSM/projects/6#column-4776614