Correct matching with species-table genus,species,cultivar,gender and powerline_conflict_potential.

Although I know you are working on "importer" as an eventual replacement for uimport, here is a fix for two problems I encountered in the current 1.3 uimport.py: 1) a confusion in the function check_species between the species object and the species field which produces an erroneous match, and 2) an error in referring to the powerline_conflict_potential field that prevents setting it properly. I have also amplified the discussion in uimport_doc.txt (I hope correctly!) on how to use the program.

Hope these changes are useful!
Bob Troester