fasterius/seqCAT: seqCAT version 1.6.0

This is the fourth release of the seqCAT package, which follows Bioconductor's "even-release, odd-devel" version scheme and is equivalent to the 1.6.0 release on the Bioconductor website. It includes the following additions and changes:

• Rename several function arguments to increase clarity
• Make filtering of variant calling-specific quality metrics optional
• Add a check to validate if input VCFs are genomic VCFs
• Add checks to validate if input VCFs contain data on variant depth, allelic depth and genotype data