Issue #775 fix 

Checks are now in place that assure with logger.errors/warnings that:
 -there are not duplicate species in the selected PFTs (error)
 -the selected PFTs cover all species expected by the FIA db (error)
 -the selected PFTs do not have species not expected by FIA (warn)

In any of these cases, a simple lookup table matching species names
to scpds is read (species_names.csv) to output the names of the
trouble species with a nicely-formatted message. This can be modified
to be done with queries to bety/species instead - I can't tell which is 
costlier. Execution is stopped after the logger.errors. Test cases are 
enclosed in pft_consistency.R