General cleanup

[chipbarnaby]

Review/eliminate unused code

• wfpak -- packed weather file support, including wf_PackedOpen() and callees.
• Convert myriad #defines to const int or constexpr int (need clear policy)
• Migrate SI to int
• Re-code stand-alone C-style declarations, e.g. "int iVal; iVal = argVal" -> "int iVal = argVal;" (or int iVal{ argVal};'
• Eliminate little-used data types e.g. WFLOC
• Experiment with / use HPWH estimate output temp
• Generalize use of Courier
• Document DESCOND
• Document $ vars