Fix whitespace, enforce uniqueness of key column.
Fix whitespace, enforce uniqueness of key column.

reubano/csvkit,wjr1985/csvkit,archaeogeek/csvkit,wireservice/csvkit,matterker/csvkit,gepuro/csvkit,kyeoh/csvkit,metasoarous/csvkit,doganmeh/csvkit,tlevine/csvkit,cypreess/csvkit,jpalvarezf/csvkit,themiurgo/csvkit,Jobava/csvkit,bradparks/csvkit__query_join_filter_CSV_cli,snuggles08/csvkit,bmispelon/csvkit,elcritch/csvkit,aequitas/csvkit,arowla/csvkit,dannguyen/csvkit,moradology/csvkit,KarrieK/csvkit,onyxfish/csvkit,barentsen/csvkit,Tabea-K/csvkit,unpingco/csvkit,haginara/csvkit,nriyer/csvkit