Add ruby overload for value=

Expose UserModel.loadWeather()
rename max to avoid #define confusion

expose weather data in UserModel so that scripts have access
add unit testing and unit testing resources for Sim and User Models.
Update example model with a valid dhwSystemEfficiency

Update unit tests to reflect new data
Add a flag to indicate whether the user model loaded successfully
Update to use std::strings instead of char*

change #define DEBUG to be project specific
Add comments to public functions
Update loading of weather file to accept an absolute path or a semi-relative path (relative to the ISO file)
Add require isomodel module to ruby scripts.