Color points by species

[jdeck88]

Request from Dusty McDonald and Sylvia Brunner:

A color by species option would count the number of unique species (using values from the darwin:scientificname property from the configuration file) in a query and assign each of these species a distinct color, and then display the species names & colors in the legend on the left.

This would work well in cases where there are just a few species but may get messy if there are dozens of distinct species. This may not really be an issue... but we could apply a hard-limit of 100 distinct species, at which point the application would say "Invalid option, too many species to map" .