Hotfix/vic 4.1.2.h

Updates for release of hotfix/VIC_4.1.2.h (relative to 4.1.2.g):

* src/calc_root_fraction.c: Fix for infinite loop that occurs when the total of root zone depths exceeds the total soil depth and one of the root zone boundaries coincides with a soil layer boundary.
* src/global.h: Updated release version string.
* src/initialize_atmos.c: Fixed bug in the case of user-supplied daily specific or relative humidity without accompanying average daily temperature (with which to convert these into daily vapor pressure); in this case, the interpolated sub-daily vapor pressure from MTCLIM was being used instead of vapor pressure computed from the supplied humidity.  Now, daily specific or relative humidity are converted to daily VP right before the interpolation of daily VP to sub-daily.  If sub-daily humidity was supplied, it is converted to sub-daily VP after the interpolation of MTCLIM VP, so that it overwrites the MTCLIM VP.
* src/mtclim_vic.c: Fixed bug in shortwave computation for case when daily shortwave is supplied by the user.
* src/mtclim_wrapper.c: Fixed bug in shortwave computation for case when daily shortwave is supplied by the user.\
* src/README.txt: Updated to describe contents of this hotfix.