Re-starting Planner mySQL access

It's a year since I last did anything towards trying to get Planner to work with mySQL as the database backend in place of PostgreSQL. After getting it to work successfully it was too disheartening to find my source code lost in a drive crash (and without any backup).

A year on, the mySQL access is still not there so I'm trying to re-start - afterall, I did have it reading from & writing to mySQL (though the code was not very tidy) and I can remember (sort of) what I had to change to do it. So this is an opportunity to re-do it and hopefully better.

First things first though.