added lightME and weachDT functions from BioCro/Wimovac for calculating light macroenvironment and for downscaling met drivers from daily to hourly
Merge branch 'master' of github.com:PecanProject/pecan
merge
added vignette that will demonstrate how to check that a met driver complies with CF/PEcAn format
added PEcAn.DB as dependency for PEcAn.BIOCRO
Merge branch 'biocro-module2' of github.com:PecanProject/pecan into biocro-module2