* Writes as ";"-delimited string rather than the Python list representation
* Writes non-existent or "PASS" filters as "PASS" rather than "."
Modify Writer to output INFO field properly:
* Writes Flag outputs just as present, not using the X=Y format
* E.g. the DB flag to indicate presence in dbSNP will be written as "DB", rather than as "DB=True"
Modify Writer to allow different line terminator to be used:
* Default remains "\r\n" for backward compatibility