Update to vega_check.pm
Added allowed combination for various IG and TR genes to the ensembl_extension
hash. This means that gene and transcript biotypes such as IG_C_gene, TR_V_gene
etc are not flagged as problematic. Also fixed a bug in the ensembl_extended hash
where there were duplicate keys for protein_coding and processed_transcript and
this caused the first set of values for each duplicate key to be overwritten.