Updated vcf-to-proteindb to parse using pandas

[husensofteng]

• Pandas dataframes are used to work with the VCF records therefore, the older pyvcf package is no longer needed
• Also, variants can be filtered based on the biotype of their overlapping transcripts (only for pre-annotated VCF files) since only protein-coding transcripts are used to translate unannotated VCFs. -Updated some fields including variant filtering and default values.