External bug - investigate impact ?

[evezeyl]

nucdiff formating of vcf variant files that are then "prepared" aka, fix the format, before annotation with vcf-annotator has "bugs"
This is fixed with prep_vcf_annotator.py

1. Adding info Column
2. To investigate : in some case N is writen in REF and its NaN in ALT - This makes vcf-annotator bug. I fixed this by replacing NaN by "."
   But this might not bee good
   For eventual analysis of annotated snps, - REF with N must be then filtered out
   This also means that some differences might not be true ... errror - we need to find a way to validate

[evezeyl]

commit fix: ddc9ded