Try to rework atm2lndType initialization to follow the typical pattern

**Bill Sacks < sacks@ucar.edu > - 2017-10-26 13:55:27 -0600**
**Bugzilla Id:** [2527](http://bugz.cgd.ucar.edu/show_bug.cgi?id=2527)
**Bugzilla CC:** andre@ucar.edu, erik@ucar.edu, rfisher@ucar.edu,

Motivated by bug 2526:

I noticed that the initialization code in atm2lndType doesn't follow the typical CLM pattern. Specifically, initAllocate initializes these variables to 0, then initHistory can overwrite these 0s with spval; there is no initCold. Typically, initAllocate would set these to NaN, and there would be an initCold after initHistory.

We should try to bring this more in line with the typical pattern. One reason to do this is to prevent accidental behavior changes that arise simply from adding or removing a history field (and thus by adding or removing the setting to spval).

I hope this won't change answers... but I am worried it might. If it does change answers, this likely suggests that some spval's have been leaking into the code where they shouldn't, maybe due to accumulator variables (see also bug 2526).