Improve handling of blank values and disallowed INFO characters
Improve handling of blank values and disallowed INFO characters

Previously, values that were totally blank did not get translated
to VCF correctly. They will now get translated to a singe period,
which represents a blank value in a VCF. Handling of disallowed
INFO characters has also been improved.

sephraim/bin4matics,sephraim/bin4matics