Program must fail hard when encountering error in single-point weather data file

[smwesten-usgs]

The program will continue to process a single-point weather data file even if the required header labels are not found. This results in phantom data values being fed into SWB, essentially whatever nonsense values happen to be in the memory space that was allocated for the precip or temperature data.

Failure example:
A file with
date precip tmin tmax
for the header was fed into the program. The run continued, although no precipitation data were read in (it was looking for a column of data labeled 'prcp').