Switch parseVEP to using column names

[lydiayliu]

#Uploaded_variation  Location    Allele  Gene                Feature             Feature_type  Consequence                         cDNA_position  CDS_position  Protein_position  Amino_acids  Codons   Existing_variation  Extra
1_12299290_C/A       1:12299290  A       ENSG00000048707.15  ENST00000011700.10  Transcript    stop_gained                         2590           2591          864               S/*          tCa/tAa  -                   IMPACT=HIGH;STRAND=1;SOURCE=GENCODEv34
1_12299290_C/A       1:12299290  A       ENSG00000048707     ENST00000011700     Transcript    stop_gained                         2590           2591          864               S/*          tCa/tAa  -                   IMPACT=HIGH;STRAND=1;FLAGS=cds_start_NF
1_12299290_C/A       1:12299290  A       ENSG00000048707.15  ENST00000460333.5   Transcript    non_coding_transcript_exon_variant  10             -             -                 -            -        -                   IMPACT=MODIFIER;STRAND=1;SOURCE=GENCODEv34
1_12299290_C/A       1:12299290  A       ENSG00000048707     ENST00000460333     Transcript    non_coding_transcript_exon_variant  10             -             -                 -            -        -                   IMPACT=MODIFIER;STRAND=1
1_12299290_C/A       1:12299290  A       ENSG00000048707.15  ENST00000613099.4   Transcript    stop_gained                         6252           6122          2041              S/*          tCa/tAa  -                   IMPACT=HIGH;STRAND=1;SOURCE=GENCODEv34

We currently just use "the first 13 columns"