Change weather.retrieve so that can customize pre.agg calculations and lag term calculations.  Completely rewrite create.cols.weather, so that it will match whatever is specified in pre.agg, agg; flow retreival can be easily customized without needing to change the create.cols function.
rebuild package with updates to weather retrieval
rebuild package, customized flow and weather retrieval (rebuild 2)
data merge modification for flow/basin or weather/basin-only merges. simplifications for flow and weather agg ddply calls, date templates.