Multiple validation levels and more errors/warnings handled

This version introduces support for different validation levels: check only errors, errors and warnings, or stop after the first error is found.

The previous version didn't handle properly all the corner cases in meta-data descriptions. Empty descriptions and those containing escaped quotes are now considered valid.

Warnings are now raised when:

• A comma is found in the ID column
• The POS column value is zero

Please check the milestone information for a detailed description of resolved issues.

Working version for VCF 4.1 and 4.2

First working version of the validator, supporting VCF 4.1 and 4.2 via a formal grammar implemented using the Ragel State Machine Compiler (http://www.colm.net/open-source/ragel/).

It has been tested against all the files submitted to the European Variation Archive (www.ebi.ac.uk/eva) up to this date. More stand-alone tests are being implemented and will be included in future releases.