add scripts to make sacCer3_VCF db

This commit updates the sacCer3_VCF variant database such that the VCF files for each strain only contain unique, unambiguous variants. The full, original VCF files are moved into a subdirectory `sacCer3_VCF/full_VCF`. Also included in this commit are scripts to regenerate these databases from scratch.

sacCer3_VCF/*.gatk.vcf
-These are the unambiguous variants for each sacCer3 strain
sacCer3_VCF/full_VCF/*.gatk.vcf
-These are the full VCF files saved for reference
utility_scripts/generate_sacCer3_VariantDB.sh
-This bash script downloads VCF files from SGD, parses them to convert chromosome naming from roman to arabic numerals, and strips out ambiguous  variants with bedtools intersect
utility_scripts/parsers/parse_sacCer3_VCF.pl
-This is the perl script for converting the chromosome naming system of the VCF files

Author: owlang