Site-specific inputs for latitude, altitude, slope, and aspect

[kpalmqui]

This issue will allow site-specific inputs for latitude, altitude, slope, and aspect for each site. Currently, these values are fixed within rSFSTEP2, as the default settings in siteparam.in are utilized.

This issue will create a new input csv file where the user can populate the site-specific values and will also add new code to ensure the necessary input files (siteparam.in) are derived for each site in Main.R and then placed in the appropriate folder prior to executation of STEPWAT2 in CallSTEPWAT2.R.