added functions for regridding data, and also for writing gridded data (array) to netcdf
merge
Merge branch 'master' into biocro-module2

Conflicts:
	utils/R/regrid.R
added example pecan.biocro.xml
add conditional to only use filter.sunleaf.traits in query.data on SLA and Vcmax if there are canopy layer covariates.
explicitly state db parameters in each test file
updated workflow vignette
Merge remote-tracking branch 'origin/master' into biocro-module2
changed default sample size for derive traits from 100k to 10k in order to speed up conversion, e.g. of c2n_leaf --> leafN.
updated biocro module rscript and model2netcdf