The default ilwr model in Atmosphere as been changed to Unsworth. The fixed...

The default ilwr model in Atmosphere as been changed to Unsworth. The fixed snow albedo has been set to 0.85 for all filters/generators using it. 

The Config class can now import an ini file from another ini file, this could greatly simplify the management of operational deployments (a station that has a special configuration now can simply import a standard config file and redefine what it needs). This is either done with IMPORT_BEFORE or IMPORT_AFTER in order to choose who has precedence. Multiple (ie recursive) inclusions are supported with some enforced limitations to prevent circular dependencies.