small changes in simSV: Avoiding mutations in N positions & make SNP positions in the printed VCF as 1-based & SAMPLE in header

[sinamajidian]

Dear Fritz

I'm suggesting following changes in simSV subprogram of SURVIVOR:

• Avoiding mutations in N positions in the input reference FASTA
• making SNP positions in the printed VCF as 1-based
• Adding "SAMPLE" as the last column in header of VCF

Regards, Sina