Fix crucial column header in metadata.

data/metadata.csv

@@ -1,4 +1,4 @@
-Sample_ID,sample_id_prefix,rep_num_in_2017_paper,external_id,species,technology,pipeline,fastq_generation,genome,genotype,source_tissue,perturbation,diff_protocol_human,eday,dissection,dissociation,FACS_sorting,RBC_lysis,parathyroid_present,sequencing_date,transcripts,cells,umis_in_dge,umis_per_cell,any_female_cells,notes,files_available,dge_path_rel,tcr_dge_path
+Sample_ID,sample_id_prefix,rep_num_in_2017_paper,external_id,species,technology,pipeline,fastq_generation,genome,genotype,source_tissue,perturbation,diff_protocol_human,eday,dissection,dissociation,FACS_sorting,RBC_lysis,parathyroid_present,sequencing_date,transcripts,cells,umis_in_dge,umis_per_cell,any_female_cells,notes,files_available,dge_path,tcr_dge_path
 e12_5wholeThy_venus,E12_5_wholeThy_venus,1,E12_5_wholeThy_venus_1,mouse,dropseq,dropseq,illumina,,Pax9-Venus,embryo,NA,NA,12.5,thymus and parathyroid by mechanical separation,trypsin,Live cells,no,yes,2016MAY03,15865,576,2816244,4889.3125,no,,yes,GSM2883184_E12_5_wholeThy_venus_1.dge.txt.gz,GSM2883184_E12_5_wholeThy_venus_1_tcr.dge.txt.gz
 e12_5wholeThy_venus_rep2,E12_5_wholeThy_venus,2,E12_5_wholeThy_venus_2,mouse,dropseq,dropseq,illumina,,Pax9-Venus,embryo,NA,NA,12.5,thymus and parathyroid by mechanical separation,trypsin,Live cells,yes,yes,2016MAY28,15501,276,2273615,8237.735507,no,,yes,GSM2883185_E12_5_wholeThy_venus_2.dge.txt.gz,GSM2883185_E12_5_wholeThy_venus_2_tcr.dge.txt.gz
 e12_5wholeThy_venus_rep3,E12_5_wholeThy_venus,3,E12_5_wholeThy_venus_3,mouse,dropseq,dropseq,illumina,,Pax9-Venus,embryo,NA,NA,12.5,thymus and parathyroid by mechanical separation,trypsin,Live cells,no,yes,2016AUG10,16001,895,3604897,4027.817877,no,,yes,GSM2883186_E12_5_wholeThy_venus_3.dge.txt.gz,GSM2883186_E12_5_wholeThy_venus_3_tcr.dge.txt.gz