Compile module, subroutine, variable info from HSPF manual

[aufdenkampe]

HSP2 uses all the same codes as HSPF for modules, subroutines, variables. These codes were created back when file names were limited to 8 characters. Understanding what these codes mean is an obstacle to using HSP2.

We've been compiling this information largely by copying & pasting from the HSP2 v12.2 user manual into the HSPF Modules & Variables Google Sheet, but still need to complete Input variables, especially for Geographic inputs.

This is a first step to adding inline documentation into the code and also starting to automate data pipelines to set up models.

[aufdenkampe]

@McGrupp10 (Nick), could you start working with @derekschlea to fill out the Input-Geographic tab in the HSPF Modules & Variables Google Sheet? I'm hoping that you can start by copying and pasting from tables in the manual, following a similar approach to what I did for the Input-TimeSeries tab.

cc: @steveskrip, who helped get the Google Sheet started.