Fix the bug of error when only run the model for only a single gridcell.
Add some function to calculate Nash-Sutcliffe coefficient of efficiency (NSE) and relative bias (RB) to evaluate the streamflow simulation performance.
Longwave radiation and atmospheric pressure are not necessary forcing input now (can be estimated by elevation, air temperature, vapor pressure and solar radiation).
Fix some codes with bug or potential problem of the VIC source codes.
Fix the data error of the STEHE sample data.
Add the observed streamflow data to STEHE sample data for routing model.