Make it possible to add ecosystems that don't pop up on the map

[teixeirak]

The calculator is not (and never will be) perfect at predicting which biomes could present in the location where a pin is dropped. We need the option for a user who knows what should be there to add it. (For example, Barro Colorado Island in the the middle of the Panama Canal does not have any ecosystems associated with it. User needs to be able to add tropical forest there.)