Validate csvstat args before processing. Closes #277.
Validate csvstat args before processing. Closes #277.

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