Outline script
Add sample bam file for testing
Add sample FASTA reference file for testing
Add expected FASTA output file for testing
Test extraction: 10bp upstream of reads (P:0/1)
Get options from CLI
Parse bam file
Get read info
Add scaffolds for subs extract_flanking_seqs & write_to_fasta
Get start/end positions for FWD strand seqs
Get start/end positions for REV strand seqs