water year restart hour

[scotthavens]

Similar to issue #52, specifying the water year hour with wyh_restart_output should be updated. AWSM should take a restart date and parse it into a water year hour if it's needed. That is one less step that a user needs to take.

For example, to restart one must first determine the water year hour on the command line:
> wyhr 2010-12-29 23:00

then plug that value of 2159 into the config file. It would be a lot cleaner and verbose if it was
restart_output_date: 2010-12-29 23:00 or something along those lines.