NHC ATCF BTK File Fix

[mattbilskie]

1. Replace 0 pressure in NHC atcf best-track with standard atmospheric pressure.

When generating the fort.22 in adcirc (NWS=20), aswip does not like values of 0 atmospheric pressure. Under this condition, aswip will not complete the generation of the fort.22.

2. Fill in the forecast hour column and replace the date/time column with the start date/time for all time snaps. This is necessary for NWS=20 fort.22 file generation.