Remove extra _spid column added by richness_in_group
Remove extra _spid column added by richness_in_group

Due to aliasing this column can end up back in the originating DataFrame,
which can be confusing.

rueuntal/macroecotools,rueuntal/macroecotools,weecology/macroecotools,weecology/macroecotools,davharris/macroecotools