Added support for BLOB and irregular dates

I have added support for converting BLOB into either a configurable datatype or this what the user can enter while the script is running.
Also I added handling for MySQL's 0000-00-00 and YYYY-00-00 values, since they are not supported by Postgres. They are either replaced with a configurable other date string, or the column is made nullable and null is set to default. What this not does, is replacing the values in the INSERT-statements.